we've transitioned before from CentOS 7 to Rocky 8 and it was not too bad, mostly just a good amount of planning and testing. we've got about 160,000 cores between 2 clusters (1277 nodes that i help manage, and 825 that are located at a facility that handles hardware for us) -- fortunately I do primarily hardware work so don't deal with the software headaches myself, and the people that do are very capable - but typically you'll have incompatibilities, and a lot of user support stuff for the first couple weeks until things smooth out.