Hello, since some days ago, after last wordpress update I think, sometimes my site shows this kindof ¿Ascci? code.
After refreshing the browser sometimes it is ok some times it still the same.
You could try testing for a plugin conflict. You can do this by deactivating all third party plugins, and seeing if the problem remains. If it’s fixed, you’ll know a plugin caused the problem, and you can narrow down which one by reactivating them one at a time.