Sounds like another case of My fairphone 6 died suddenly
I hope it was not green too 
. Did the screen got a bit hot? I stopped using fast charges after if got replaced. My fear is that having forced slow charge on the phone and chargers who might not sync it blows the SoC. But no clue, just a random guess as it happened to us all with chargers connected and my case was a fast charger, and even with this mode it was topping up fast.