When there are people that you should enforce (reward/punish) good and bad ideas or persecuting (deplatforming) those that don't think like them, that's the thought police. It comes from George Orwell's warning, the dystopian novel Nineteen Eighty-Four, on how the turpid philosophy of collectivism (marxism, socialism, progressivism) historically permeates a society and infects it with their tribal intolerance towards "others"; the bigotry and scapegoating that lead to the rise of most despots and the rationalization the masses used on persecuting minority groups. In the book, they are a secret police of the superstate Oceania, who discover and punish any personal or political thoughts unapproved by the collective. In America, they are out in the open, they are BLM, Antifa, the DNC, political correctness in our culture, the biases in their media, it is diversity training and champions that want to stifle intellectual diversity with litmus tests, it is anyone that wants to put their one true ideology ahead of the ideology of American Liberalism (which was about freedom of speech, freedom of expression, and agreeing that the glue that holds the nation together is letting or differences exist without the henpecking persecution of the mob). The examples are many, but the denial and lack of introspection of the followers is stronger. Almost all evil deeds were done by people that thought they were the good ones, and the others were bad. But good and evil is about actions and not intent. So I'll list some of the actions, and leave for the reader the exercise of imaging that the victim is their siblings, parents or children -- and if they are OK with this anyways, then they are evil. If they are not, and they look the other way, then they are hypocrites.
Of course the idea of a Thought Police isn't bound to political left or right. It's just that historically, the left is about collectivism, and the right about individualism. And collectivists by nature demand conformity to the collective, and enforce litmus tests to betray anyone that doesn't conform.
During Digital Kristallnacht (and the aftermath), when the Tech Giants and their flock of lessors decided that the Biden Administation coming to power was a signal to purge conservative voices, we had the following attacks. Twitter and Facebook imagined crimes not because of what Trump said on their platforms (as their side said far worse, far more often), but on what they imagine he thought and secret dog whistle signals -- and they banned him from their public platforms for those imagined crimes. Not just the posts that were offensive (because they didn't have good examples), not just the accounts he wrote them on, but his entire presence as a signal to him and all his supporters and the 75M+ Americans that voted for him: your kind is not welcome.
While the deluded claim that this was because Trump was exceptionally bad, it helps to remember the breadth of what happened and to whom -- this wasn't an attack onTrump, this was an on his supporters, on free speech, and on any conservative voices that they felt were influencers or they could make excuses for:
- Twitter also blocked Mike Flynn, Sidney Powell for not agreeing with Jack on evidence of election fraud.
- Twitter also blocked Trump's campaign account, and his campaign’s digital director -- a whole political party/movement that serves 75 million voters. 
- Facebook blocked Ron Paul from managing his FB page, without any warning... all because he complained about Big Tech censorship, on another forum altogether. It's not only about thought crime on their platform, but anywhere in the known universe. 
- Then there were many more like Kevin McCullough, Team Trump, @Techno_Frog. Just agreeing with the President on anything unrelated to election fraud is enough to get you purged. 
- Then they started sanitizing the accounts of thousands of others. People were noting that their followers were dropping off by 7,000, 15,000 or 30,000: they were being disappeared like Uyghurs in China for retweeting anything by conservatives. This was NOT just Trump, this was anyone that agreed with him too visibly. Twitter later came back (after the outrage) and admitted they were deleting accounts, but it was only of people that had ever relayed anything by QAnon. Of course they might not have known it's source, and there's zero transparency to know if that's true (and no reason to trust), and can you imagine the outrage if they did the same to anyone that relayed leftist conspiracy theories like Russiagate or who relayed the lie that Trump said neonazi's were very fine people?
- CNN was asking Cable Stations to drop FoxNews, OAN and Newsmax, to try to silence conservatives 
- Still others like Rush Limbaugh, Lou Dobbs, Greg Guttfeld and Mark Levin were driven off: decided they should abandon the platform of fascism, before they were digitally lynched.
- Facebook and Instagram followed suit... then took out the entire #WalkAway campaign with hundreds of thousands of followers, videos and testimonials of people admitting that once they opened their eyes, they had to leave (Walk Away) from the ever more fascist DNC, and why . Testimonial truths that don't fit the leftist agendas are also seen as a violation of terms, it seems.
- Snapchat also suspended him 
- Pinterest couldn't block Trump since he didn't have an account, so they started attacking hashtags that supported Trump or his ideas 
- Reddit, followed along, banning the entire Trump subreddit for non violation of terms, they just didn't want to be left out of Joe Biden's new call for unity, healing and finding a path forward (without those dirty conservatives, of course). 
- Shopify banned Trump's campaign store and his personal brand store, to join the tech mob digital lynching. 
- TikTok still mad that Trump tried to protect Americans privacy again this Chinese controlled company, started purging Trump’s speeches to his supporters when users put them up. 
- Amazon owned Twitch locked President Trump’s account indefinitely. 
- Apple, Google, Amazon coordinated an attack on Parler -- because it would have been a good outlet for conservatives to move to. This hurts that company and it's employees, and anyone that used/enjoyed the platform, or would like an alternative to the Twitter/Facebook hegemony -- all for the high crime of being more free-speech than Twitter/Apple/Google/Amazon wanted. Can you get more anti-competitive than that? Not really, but since it was done for the Big Guy and to hurt Orangeman, the Democrats are OK with that corporate abuse of power.
They didn't just attack Trump, anyone that repeats that if a fool or a liar.
Meantime, Twitter has never considered banning world leaders of the most oppressive regimes in the world, for far more offensive tweets. Be a Holocaust Denier, call for violence against conservatives (like the DNC leadership did), support terrorist organizations like BLM or Antifa, show the beheading of the President or participate in murder fantasies about "Blowing up the Whitehouse", talk about persecuting anyone who supported your political opposition, and you'll keep your status... if your attacks are against conservatives. But if you dare say that you won't bow before the lefts anointed, or defend 75M pro-Democracy voters that are being disenfranchised and put in digital concentration camps? For that, you get banned.