Photos won’t show on iPhone camera roll until a restart

Since updating my iPhone 12 to iOS 14.6 two weeks ago, every day or so photos, screenshots and downloaded media won’t show up in my photos, or the camera roll in any other apps, until I restart. And I’ve also noticed issues where viewing old photos it gives me some low res version if I zoom in.
If I restart I get the full res version again and any photos I took that hadn’t appeared in the camera roll are suddenly there.
Phone has 64 GB of space remaining and is only 3 months old with about 600 photos.