Same thing happened to our servers. Two out of three have the problem mentioned.
There is some workaround though. Domain users can be added manually, without the search through AD, so they are able to log in.
What strike me as strange is: when the domain user has the role of an Administrator it can search through the AD with no problem. But even then that user can not connect through vSphere Client when "Use Windows session credentials" is checked, only when manually providing DOMAIN\username and password, also logging in in a form of username@domain is not working on the servers affected by this issue.
We haven't tried restarting the hosts yet but we will try that when the workload permits us.