That issue where Google was labeling pages as not mobile friendly when they are is still maybe an issue? I am seeing new widespread reports in the Google Webmaster Help forums, dozens of threads of complaints of sites that are mobile friendly according to the mobile friendly tool but are being labeled as not in the mobile Google search results.
Here is one example from @danmozgai but there are tons of examples in the threads linked to above.
Google labeling AT&T as not mobile friendly in the search results:
But the mobile friendly testing tool shows it as mobile friendly:
Heck, even my AMP page is marked as not mobile friendly - how is that?
The one thing I saw in common, with the exception of this example is that they all have red colored page speed scores. But like I said, there was at least one exception, so I am not sure.
Here is AT&T's score:
So why mark it as mobile friendly in the mobile friendly testing tool if it is not mobile friendly in the search results Google?
I asked Google about this but have not yet heard back.
Update: This was a bug on Google's end and so John Mueller said they disabled the label for now until they fix it: