If you install KB5020023 on a Windows Server 2012 R2 Domain Controller, this can stop you from being able to log into other computers (even if they don’t have the KB5020023 update installed on them).
To fix this, I uninstalled the update from the Domain Controller, but I read that there’s also an Out-Of-Band Windows Update available to address this problem. The reason I uninstalled the update rather than installing the OOB update is that the wording on the OOB update inferred that it could cause other issues or not really fix the problem (the wording said that it would “improve” the situation). Microsoft inferred that they may bundle a fix for this in the future some time.
More details on each from Microsoft for each, here: