The battery, after ailing for a little while, had eventually just given up. I'd gone skiing a couple of times, with the last trip being just before lockdown, and I think it was the cold exposure of the second trip that dealt the mortal blow, and it died shortly after I returned.
I liked that phone a lot. It did, at the time, everything I needed, and it was a really nice size, but that period in 2020 was a bad time to try to get a phone repaired. I did attempt to replace the battery myself using the guide on iFixit but, sadly, that did not go well due to some contradictory/out of order instructions, and all I succeeded in doing was damaging the phone, I think, beyond repair.
Really good to see that Apple are still supporting them though.