Brief unthemed text when launching Fiori application

Recently, I've started seeing a brief view of unthemed text slammed together when opening a Fiori App. This has only happened for the last couple weeks. I wasn't able to find any information on what may be causing this. Any ideas? Note: it seems to only be happening with Fiori tiles that use the web gui, so may not be a Fiori issue at all.

Changes in the last couple weeks: kernel swap (seems unlikely to be the culprit), browser updates to Edge and Chrome.