They limit the results to like 5-10 videos and then replace the rest of the results with irrelevant videos under the "People also watched" tab where the results are the combined list of random words from the search query and "From related searches" tab where it's just random videos that belong to the same category of videos. This means that unless you're extremely blessed by the algorithm your video has basically no chance to show up in the search results, even if is relevant!
The weirdest thing is that the old search isn't even gone! You can still get relevant results after clicking "Filters" and then "Videos" in the "Type" column.
Who is this feature even for and what was the motivation for doing it? From the perspective of an actual user it makes no sense.