The 1 or 2 kB of lyrics are a few orders of magnitude smaller than the song being streamed.
The album art probably takes up more space than the lyrics.
So, album art should also be a paid feature?
Because it improves the experience, but isn't vital to it. If you want the free tier to be accessible to everyone, limiting things like lyrics that people like OP use as a disability accommodation isn't the way to do it.
The whole point with features being paid for is that they incentivize you to pay. There is no universal right to have a free tier or certain features for free.
It just makes sense to lock features that users enjoy to incentives them to pay.
It’s unfortunate and I can empathize with the user but I don’t see it as obvious that this specific need should be catered to, for free. It’s primarily a music service and lyrics is an additional service to enhance the experience, apparently at the paid-tier. It’s not so expensive that it’s inaccessible to the average user, if music with timed lyrics is an important part of their life.
I don't know. If we were talking about Netflix making captions a premium feature that requires an extra fee, I'd think that's pretty skeevy and ableist. I hadn't thought about lyric sheets being an accommodation until OP brought it up, but now that they did, I'm kind of putting it in the same bucket.