Google's John Mueller said that if your page passes the live mobile usability test - that means you can ignore the Search Console notices of "new mobile usability issues detected for site." So as long as you pass the live mobile friendly test, you are good to go.
John said this on Twitter:
I have a long explanation about why that can happen, but the short version is you can ignore those warnings if the live test passes.
— 🧀 John 🧀 (@JohnMu) September 11, 2021
Here is what those notices look like:
John said to Terry "I have a long explanation about why that can happen, but the short version is you can ignore those warnings if the live test passes."
Why might it pass the live test and you would get these notices? Well, those email notices can be days late from what you might see on the live site. So if you fixed the issue already, and the live test picked up on it, then you are good.
Forum discussion at Twitter.