It's just blind speculation. There is absolutely no historical precedent of Big Tech corporations implementing censorship controls at the behest of governments. Anyone claiming otherwise is spreading misinformation and should be censored.
Government already admitted to pointing Facebook to accounts to be deplatformed. Government and social media collusion is now best assumed to be going on. All that matters now is how much the companies are incentivized to push back. The answer: not much.
If this change happened or not due to such collusion is secondary to the thing worth noting: it would not be surprising if it did, it would be consistent with the governments positioning if it did, and it would also be hard to prove if it did, and if it was proven it would be vociferously defended by legions of commentators and the media. All that would need to happen was for the government to suggest the downvotes on pro-vax vids were contributing to deaths and ergo liability, and suggest the whole feature serves as a mechanism for disinformation they may be liable for in general, perhaps criminally so if the feature can be traced back as a proximate cause of something like the capital riot. Poof.
>Google representatives attended White House meetings more than once a week, on average, from the beginning of Obama’s presidency through October 2015. Nearly 250 people have shuttled from government service to Google employment or vice versa over the course of his administration. [...] The government and Google shared engineers, lawyers, scientists, communications specialists, executives, and even board members. Google has achieved a kind of vertical integration with the government: a true public-private partnership. [0]
>MS. PSAKI: Sure. Well, I would say first, it shouldn’t come as any surprise that [The White House is] in regular touch with social media platforms — just like we’re in regular touch with all of you and your media outlets — about areas where we have concern [1]
>So it is possible YouTube removed dislikes it deemed "spam" from videos posted by the White House account, including the Jan. 20 press briefing video. But there is no evidence YouTube deliberately removed authentic dislikes from the video to support the Biden administration or silence critics. [2]
That is speculation, not circumstantial evidence. Thank you for providing sources that say "there is no evidence YouTube deliberately removed authentic dislikes."
You have to make reasonable inferences when evaluating the potential for collusion between what are arguably the two most powerful entities in the world.