Sensors keep failing

I've got an issue where various sensors appear to fail on the watch. Typically I don't notice until I'm mid activity and realise that the heart rate isn't recording. This morning I noticed that the SPo2 had not recorded overnight, and nor had the breath rate (heart rate was fine, as were sleep patterns). This started a few months back and I discovered then that, annoying as it was, I could restart the watch and they'd all come back up. There would be holes in my recorded data but things would be functioning.

This morning when I noticed the breath rate being off I sighed and restarted. But now I'm incredibly annoyed because it appears the watch has forgotten the entirety of this weeks sensor data, including intensity minutes and then went and synced that to the app which forgot it all too. I was in the app last night entering data so I know it was all there. All my activities remain - with all the data for those but apparently I did nothing intense this week. Ha.

It was bought back in October so is still in warranty. Is this a hardware issue? Or software? The fact it started playing up after an update (and there are other posts on here that claim the similar issues) tells me it might be a software thing?

Oh, I've also got that issue where it's failing to record my heart rate during a run properly. I'm pushing up against my limit and the watch claims I'm at 81 BPM - I wish. I'll finish, hit stop and it jumps right up to 170.