The new version (26) of the oculus software causes regular 'flashes' in Microsoft Flight Simulator. This seems to be an issue with the oculus software, since in the previous version (V25) this issue was hardly there.
Today the new version of the Oculus software was released, and so I was prompted to update to the latest version. There doesn't seem to be a way to revert back to 25 again, nor is there a beta version which solved the problem. Since I mainely use my Rift S for MSFS, my VR experience is pretty much ruined.
Here's a video somebody made who has the same issue:
There is also a thread on the MSFS forum which discusses this matter. It seems to be affecting all people who run the Oculus software in combinaton with MSFS:
And there is a thread about it on the Oculsu forum as well: https://forums.oculusvr.com/t5/Oculus-Rift-S-and-Rift/MSFS2020-Flashes-Again/td-p/837964
I hope somebody is going to look into this. Thanks in advance!
Here's the link to the pdf with the solution: https://drive.google.com/file/d/1-lCN98TJ3BiHW6eD49oOib2UsZpe6RBq/view
Thanks to Michelapole818 on the MSFS forum