Yesterday morning I was getting gmail notifications, but somewhere around midmorning to early afternoon, they just stopped. I haven't changed any of the settings, so not sure why they would stop.
What have you tried to solve this? Sometimes you can restart your way out of bugs. Restart the phone and/or the app.
What app are you using for email? I know you haven't intentionally changed any settings but app updates, unexpected app closings and other random odd things can cause settings to spontaneously change. For me, I had a month where all of my email accounts in this one app stopped receiving and I had to enable communication each separately. You may not have to go through your settings per se but definitely check if your accounts are active in the app to be sure they are even looking for new mail.
Without knowing too much about this without your answers, my first suggestion would be a simple phone restart. Restarts clear caches and close processes that need ended and restarts processes that have become stale. The next thing would be to clear the email app's cache. To do this go to Settings>Apps>{find your email app}>Storage>Clear cache.
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