It has been that way for a while now. I see Veritasium video titles and thumbnails change quite often, it can be quite annoying as it sometimes gives the appearance of it being a whole new video.

A/B testing a title feels wrong to me, its almost as bad as A/B testing a UUID. Just pick a title and stick to it unless you need to fix a factual error.

Titles and thumbnails have a huge impact on video performance, and when it's your main income it seems reasonable to try to marginalise the impact.

And video performance = ad revenue.

Right, but then there's this thing called "shared reality" and once you break it, all kinds of bad consequences happen.

This is even worse, as it also breaks temporal continuity for individual reality. E.g. I expect that if I saw a video titled X today, I'll be able to find it under title X tomorrow, and if I can't, it's one of the rare/marginal cases when it got banned/deleted/retitled, or I just misremembered. Titles becoming unstable in the general case is a bad situation.

Gaslighting is now a government policy

Oh yes. Some channels cycle through many different ones as they test them. Veritasium is notorious for this.