Very highly likely it is related to the missing files. Please keep in mind that you also need to change the mentioned line to /opt/omd/versions/<2.3.0-version>/lib/pnp4nagios/process_perfdata.pl (see other). Otherwise it will not work. It will take some time until all the backlog is reduced, and then all should be back to normal.
You can also run perl -le 'use RRDs;' as a site user. If this runs an error, then please double check if you performed all actions as recommended.