I've had problems with youtube search recently, but because I use google more often it's so much more obvious with google search.
Like I hate how they have that bar that keeps changing different search modes, before 'images', 'videos' used to be in a fixed position, now I have to go searching for it in a soup of unrelated words like 'Finance', 'Flights', etc.
YouTube doesn't really care if the search function gives you the right or wrong search result. Totally irrelevant as long as you click something, anything and your eyeballs are on the next ad. YouTube is optimised for keeping you watching ... literally anything... as long as they can play you some ads, preferably expensive ads.
And trying to increase its usability and profitability outside of ads would affect negatively Google's overall business.
In my experience the UX for google products has been an absolute dumpster fire for many years. I switched to DDG half a decade ago because I literally kept tapping/clicking on the wrong things constantly in the Google search interface. In other words it was so bad that I decided to switch even before the latest drop in the quality of search results, purely because of the UX.