Some years ago Yandex.Music had a dedicated section in the sidebar, where you could read the lyrics of selected song. It was not very full, and that is probably why it was removed.

I have created an add-on that restores this feature to its original location after discovering, by chance, that the lyrics were still available on an inaccessible part of the website. Naturally, lyrics are not available for songs that are more recent or less well-known because this database is no longer updated and used.

I don't know JS at all, so the code is, shall we say, not the best.