Casey Markee shared a screen shot of his inbox showing how he had repeated notifications from Google Search Console telling him to "fix long page titles" on a website he has verified access to. I am not sure if these notifications are new, for some reason, I am thinking they are not but I have not seen one of these.
Here is his screen shot that he shared on Twitter:
The funny thing here is that Google downplayed the length of title tags when they somewhat confirmed they extended the snippets to 320 characters.
But I guess if they are 600+ characters long, it can be confusing for your users and Google when trying to determine what your title in your snippet should be in the search results.
Have you seen these notices before?
Forum discussion at Twitter.