I think it is hard to make reasonable used lens market evaluation during the covid area. Given how well the EF lenses work on the new cameras I would predict lens value will surely fall versus 2-3 years ago, but I'm not sure how much. The lower supply items I would guess hold up stronger unless there's a RF direct replacement.
I haven't bought anything in a while. My last purchase was a 85 f/1.8 in January new that I thought was a smokin deal at $269.
Dave