I started having issues with flashing lately, too. Then I found this-- How to Configure MSFS for VR - Channel LFD
I followed most of the advice (except for adjusting the page file) about windows and openxr and the Oculus stuff and the nvidia control panel settings and haven’t had an issue with flashing since. I’m not sure which particular setting cured the flashes…I was too anxious to get back up in the air to do a proper test. Sorry.
Be advised…one of the settings in the article will reset your registry key that points to your .json file. Oculus link won’t work until you modify that registry key.