LetsEncrypt is revoking certain certificates due to a bug in CAA code on the 4th of March. You can read more about the details on this here: https://community.letsencrypt.org/t/2020-02-29-caa-rechecking-bug/114591
Public announcement: https://letsencrypt.org/caaproblem/
What should I do?
You can use this service to easily check whether your domain is affected: https://unboundtest.com/caaproblem.html
Whenever it is affected, make sure to remove the certificate from the Ploi UI and request a new one.