I just replaced my few months old ROG MAXIMUS XII APEX motherboard and i9 10900K CPU with the new ROG Z590-E Gaming Wifi and i9 11900K CPU.  It was unintentional and there’s a long story behind due to unrecoverable CTD from MSFS 2020 on the Apex system.

Anyway, I just want to say that MSFS 2020 does runs better on the new 8-core, lower frequency (3.5GHz) 11900K than the older 10-core, higher frequency (3.7GHz) 10900K.   Although not significantly, it does make a visual difference on performance.

Surely no need to dump your 10900K for the new one if you are happy with it.   Just in case there’s a chance, go for it as the 10900K still has a resale value.