YouTube appears be using ML SST subtitles most of the time and tends to trip over simple things like homonyms and at worst throws up its hands and just skips over difficult (noisy, cross-talk, etc.) segments. I say this as someone taking a 2nd language course where we'll watch a video together and do a worksheet and class discussion in that language after. Sometimes the instructor's reaction at the end will be "wow those subtitles were bad!"
Edit for clarity: the subtitles are in the foreign language, not English so it's not an issue of machine translation.
There's a lot of inconsistency, Channels like Tom Scott have remarkably good subtitles (Done by a team of humans), with different color for each speaker, closed captions and even colorfully describing sounds
Auto generated subtitles work a lot better for Video Essays and Podcasts than for TV style content (And it's really inconsistent, Spanish <-> English works surprisingly well as long as there aren't crazy accents in the way)
Edit for clarity: the subtitles are in the foreign language, not English so it's not an issue of machine translation.