The lyrics on Spotify play along/highlight as the song plays so you can read along in time with the song.
This is actually a vital accommodation for the hard of hearing and partially Deaf because we can often hear/feel the beat and sometimes the melody, but we don't know exactly where in the song were up to because the tune of all the versus sounds the same, or vocal breaks of "ooooooh, lalala" can be mistaken for the start of a new line of lyrics.
So if you're just reading along with a static page of lyrics, it takes a lot of mental energy to figure out what's happening with the song, especially if it's a new song you're discovering.
We've had static lyric sheets for decades, you'd unfold the sleeve in your record and try to read along as you listened, never 100% sure you were doing it right unless a fully hearing friend was there to point at the words and be your version of the bouncing ball.
So to have this technology that almost completely solves this problem for a vulnerable community... Then to put it behind a pay wall despite the fact that Deaf people are more likely to be underemployed and socially disadvantaged than the general hearing populous is just callous.
Our experience of music is fundamentally different to hearing people, and yet Spotify will charge us the same rate for a sub par experience.