When loading / refreshing the Admin UI in 8.5.1, it briefly but visibly shows a placeholder for the "SolrCore Initialization Failures" error message, with a lot of redness. It looks like there is a real problem. Obviously the message then disappears, and it can be ignored.
However, if I was a first time user, it would not give me confidence that everything is okay. In a way, an error message that appears briefly then disappears before I can finish reading it is worse than one which just stays there.
Here's a screenshot of what I mean
I suspect that
SOLR-14132 will have caused this
From a (very) brief googling it seems like using the ng-cloak attribute is the right way to fix this, and it certainly seems to work for me. https://docs.angularjs.org/api/ng/directive/ngCloak
I will attach a patch with it, but if someone who actually knows Angular etc has a better approach then please go for it