Double reboot on master update and composefs as root filesystem only on that master

Issue

During an upgrade to openshift 4.19 one of the masters is rebooted twice and the root filesystem now appears with composefs, e.g.:

# df -h
Filesystem      Size  Used Avail Use% Mounted on
composefs       5.8M  5.8M     0 100% /
/dev/sdb4       894G   47G  848G   6% /etc

Meanwhile the rest of the masters are update but without signs of composefs.
- Is this a concern for the impacted node?
- Is this a problem for future upgrades?
- Is there a role back option for this?