I see different behavior for RequestRenderMode in version 1.102 and 1.107
When I use RequestRenderMode in version 102, I see N/A on FPS after rendering stops, but when I use 107, FPS jumps.
Is there a different use of this mode in different versions?
I did fix a bug with request render mode in Fix request render for model loading by ggetz · Pull Request #11486 · CesiumGS/cesium · GitHub. You could try out the latest GitHub
main branch to see if it fixes your problem. The fix will be out with the next release on September 1.
If the problem you’re running into with request render mode is a sperate issue, I would recommend opening a new issue in GitHub.