Does the error message re-occur after resetting it to green?
You may also check the current alerts to check the time when this alarm had been raised.
André
Btw: Why did you grey out only 2 of 4 occurrences of your domain in the first screenshot? 😉
I was getting an alarm on a certificate also. I used this link to resolve. https://kb.vmware.com/s/article/2146011
I hope this helps.
Before you do this please shutdown your VCSA and take a snapshot and also take a file backup from the appliance backup utility.