Intersting. Pico 4 user here, havent updated to newest pivo 5.8 version, because i heard problems of PCVR gaming with it. So you did update it and now, problem did go away with these new nvidia drivers?
Can you please do some tests, revert earlier nvidias and see pico4 performance with MSFS. And then again, update to these new ones and see is there again performance upgrade with pico´s 4.8 update?
did you see this post of mine 1h ago? Pico 4 and OpenXR Toolkit - #141 by C0rsten