Dirt 5 has been updated to version 4.05 today by Codemasters. You can find out the complete patch notes for this update from here.
As per the official tweet from Codemasters, this update is for minor technical tweaks. It doesn’t appear that we have a changelog of what has been tweaked so we have to take their word for now. The patch size is small so you won’t have to download that much.
Dirt 5 Update 4.05 Patch Notes
A small patch for DIRT 5 is rolling out now on Xbox, PlayStation and PC, to make some minor technical tweaks. No server downtime is expected. Thank you
The game is available now for the PS4, PS5, Xbox One, Xbox Series, and PC.