The issue that IPA ran into was around unhashed passwords. It was added in 18.104.22.168, but removed in 22.214.171.124. So I'm surprised to see the same problem in 126.96.36.199. I have to assume it's "something else" that is causing the failure.
Any details as to why 389-ds-base is causing this FreeIPA WebUI problem? There have not been any changes to how passwords are changed in 389-ds-base in a very long time, and FreeIPA uses its own custom password policy plugin.