It seems in the last six hours some Googlebot instances are not in the Known bots list.
I have a rule in place to block UA Googlebot that returns Known Bot false.
For the last six hours a Googlebot coming from 66.249.75.173, 66.249.75.179, 66.249.75.177, 66.249.75.162 and 66.249.75.181 has been returning Known Bot false, when in fact those are true Googlebot IP.
Typically the missed/falsely flagged ips are later added to an allowlist, however, if more people report this problem, I think it would make sense raising an issue with engineering.
I know it happens (and has always happened) but I don’t know how often or how many people is affected by it.