Also losing camera quality and banking apps/NFC payment sucks. Absolutely not the fault of LineageOS though, they're doing the best they can within the constraints.
Banking apps seem to be hit and miss, though fortunately mostly hit. I've read stories, but personally never had any trouble with them. Sometimes they complain about the lack of gapps shit but somehow still work.
There's a larger problem though, Google both owns and controls AOSP. Of course, chances of them making it closed or introducing their proprietary services into it are extremely small, but they still are the captain who steers the ship.
If they'll decide to embed AI (in some open source form), many derivatives like Graphene and LOS may have to suck it and follow through as the more you change your fork away from source code, the harder it becomes to maintain for small team of enthusiast devs.