OK, so it appears not all Pixel 6a's with Android 14 are equal! I held off for a few weeks before upgrading to 14 thinking that I would join after any glitches had been sorted but no .... I have an unstable situation, signal loss when my phone is beside me, alarms not working etc. but it does seem to be getting better. Have checked all my settings but have now found just switching bluetooth off then on, and each alarm off then on, gives me a few more days of relative calm.As I have stated before, I have a Pixel 6a, and have had NO problems at all. Wish I hadn't said that! So the combination (more or less) is OK.
A rather drastic suggestion would be a factory reset. Install LL but absolutely nothing else and see how that goes. That would test the phone, android 14, and LL, with no other apps, data or config conflict.
edit: typo
Shame really because I have had Pixel phones for years and absolutely no problems at all until now. I would have thought as Libre 2 is a medical device, preparing for compatability by both sides following updates should be a given.