Maybe, although it's multiple people, so seems like it wouldn't be a camera fault.
Possibly it's how they are getting to me - I don't get them directly, they come to via someone else, and I think the someone else may be getting them via WhatsApp (which I don't use).
So in fact it's maybe the compression from WA, rather than an issue with HEIC? I should have thought of that before!
Ah, good shout, thanks I'll do that ๐