I find myself in the category that G-force, way up at the top there, describes, in that I'm finding it difficult to force new songs-and-music into an aging brain, but at the same time I've tired of lots of my earlier repertoire.
It feels as if the 'lyrics' part of my swede is a box, and it is full up! I used to think it was infinite.
I sometimes use a crib sheet at a soiree that I attend, but I wouldn't do it at a gig or a festival. Anyone could see that as a double standard, and I can't explain why it isn't.

I have seen people staring at their cellphones whilst LEADING at a singaround, and also staring at them to see if the singer is using the published variant, I suppose. That looks uncommitted to me, but may be just a generational thing. I suppose.

Learn the lyrics while you're young, my advice is.