This keeps on popping up several times a day. Very annoying. I press the do not ask again button and it does nothing. Using a Pixel 7 pro. I can only swipe right to get rid of it. An hour or several hours later, it pops up again. Half a dozen or more times a day.
Seems "Do Not Ask Again" would be the most applicable unless you're looking to do more investigating on where it's coming from and adjust the settings accordingly.
In any case, whatever app it is I'm assuming you want it and want it to work right so.. it's asking you to disable battery optimizations and for that you go to Settings>Battery>Battery Usage>Find and tap on the app>Choose from Unrestricted / Optimized / Restricted.
Unrestricted will stop the notification but you're giving the app permission to possibly eat away at your battery life.
You're right, it should be that simple -- but for whatever reason, your tapping "Do not ask again" isn't working correctly. I can't explain that right now -- perhaps there's some other 3rd party app that's interfering with that function? In any case, turning off that notification category (assuming it doesn't include anything else important to you) should get rid of the problem.