I have two active, public ReadyMag sites - www.locus.studio and www.theperiphery.co - and both display an aggravating behaviour - on initial [home] page load, what appears to be raw HTML code appears briefly in the browser top left for about half a second while the page loads, then disappears as the page loads. I have custom code in a widget on one of the two, but not both, of the sites - yet they both display the behavior. Both are hosted by godaddy.
usually this happens when the code inserted into the project has some syntax errors. sometimes it may be super simple, like a tiny mistake, or it may be related to the fact that the code is inserted into a wrong section: for example into section instead of before/after sections.
please review your code code and the way it is inserted to fix the issue