From Discord :
our RPC got stuck exactly 100 blocks after the upgrade, we have pruning-keep-recent = 100 on RPCs.. related? the nyx process is using a lot of CPU, but logging nothing
another RPC with lot less data behaved like this (initial gap at ~1400 is the upgrade, flatline is IAVL conversion, then at 14:20 it got stuck again)

From Discord :