We have a SharePoint 2019 farm that was upgraded from 2013 a few months ago.
User profiles are synchronized using AD import and seem to be updated correctly.
Search is crawling those profiles and also seems to be working correctly (at least as far as the crawl log goes; the only error while crawling "My Sites" is related to "Style library" not being crawlable).
The user's "My site" is accessible, but does not display all the property values that appear in the UPS profile.
The problem is that not all user properties are not reflected when searching for users.
We get the name only, no phone or title or anything else.
The only error in the ULS is this:
Not valid TaxonomyTerm from string '<some user property or another>'
It should be noted that this error seems to appear for many users that do not display this problem while searching for them.
Perhaps they where successfully crawled sometime before this started to happen.