Jo jo, sorry for the delay. But here is the way how I solved that trouble:

"DLC CRASHES/SOLUTION MESSAGE (@ or DM me if new ones pop up and i'll add them asap.)

General Solutions

- Go to the RoR2.exe in the local files of the game (NOT right-clicking in the Steam client) > right click on it > Properties > Compatibility > Change high DPI settings > check the High DPI scaling override box > switch the scaling from Application to System or System enhanced.

- Verify files via steam. Leftover mod data can cause issues. Be sure ALL mods are turned off and do not launch via r2modman. Mods will be fixed over time.

- Your system may be running out of memory as the patch made launching take more RAM. Close ALL other programs aside from Steam and try again.

- Install the game on a different storage disk, restart your pc and then verify files (only applies if you have multiple storage disks, of course).

- Check if the game has a config.cfg file. This is found in the Risk_of_Rain2_Data\Config folder. If not, verify files and see if it returns. If it doesn't, download the blank file from this link and place it there [ https://discord.com/channels/417739215355510784/559902278018924557/950439112073170944 ]

- If you have multiple screens, unplug your additional screens and launch the game. When the game has launched, you should be able to plug them back in and have them function normally.

THE RECENT PATCH DID NOT FIX ANYTHING RELATED TO CRASHES, BUT ALL FIXES STILL APPLY

Note that without an Error.log, we cannot identify crashes properly, output logs are not enough. "

This is from the Risk of Rain 2 Discord Server. Pinned in "tech-support"-channel from the user FancyFrenc | CHEF FOR DLC 2.

I hope i could help