Just a short notice from a sysadmin here: if your fs is going into read-only, your SD storing the os may be broken. This switch to read-only happens typically, when a filesystem call fails. Please watch dmesg in that case, as it still logs to ram. If there are errors during reads or writes consider replacing the card.
No it’s rarely if at all about broken SD. On openHABian/RPi, /var/log is on ZRAM, and when that’s full, it turns read-only, which is what happened here.
Okay, this is a detail i did not know - sorry for the confusion from my side.