This may or may not be related but for the several NVMe disks connected via USB behave similarly: during heavy writes they sometimes fail and get remounted as read-only under a different device path, e.g /dev/sdc1 while previously being /dev/sdb1.
The remount seems to happen due to some kind of disk failure, though for me it seems to be specifically USB related as I have several similar NVMe disks plugged into M.2 sockets with no problems what so ever.