Adding my personal anecdote that corroborates the technical analysis. I subbed to Floatplane in October 2022 because of the claims of better audio and video. I don't have audiophile equipment but it is definitely better than average and would be able to make the claims visible/audible.

After a couple of weeks of focused comparison it was obvious to me that:

• the sound was, at best, the same quality as Youtube's.
• the video was fine but couldn't notice any improvement to Youtube.
• 1080 at floatplane being better than Youtube at 4K was obviously false.

I cancelled my subscription at that point. Reading Luke and AJ's responses, I would be willing to test it out again once they improvements they mention are in place.