Makes sense that Google did this deal since their search quality tanked and they became an de facto front end UI for Reddit.
Google hasn't been a search engine in a long while, it's just an advertisement engine now.
it started when youtube removed the ability to search for videos older than 5 years, if I had to guess? cost saving, have every old video in cheaper storage... but it sort of fragments youtube, every couple of years you only get newer content.
But yeah, the most outrageous one is older videos, I do believe the reason is that they are using some long term cloud storage that is cheaper for older videos so they removed the ability to search by date.
Additionally, I don't believe the API fully fixes it, because Bing has a wrapper for youtube and searches do not really vary