Google has confirmed that messages from the Search Console about problems on mobile devices may be an error.
We often encounter a situation when the Search Console “swears” on one of the client’s sites pages. According to John Muller (one of the company’s leading experts in the field of search), such problems should not bother webmasters, if a page passes validation through verification tools, then anything can be the cause of such messages: an unloaded CSS file, a point break in the loading of part of assets, and so on. Again, if the page passes validation, the warnings will disappear over time.
Usually it’s something simple like some CSS not loading that one time when we check for MF’ness. Often it’s just a fluke, and when a site has lots of pages, some of them might see flukes occasionally. It goes away, if the page is OK.
— 🧀 John 🧀 (@JohnMu) September 13, 2021