Next thing to try…
Use Finder’s Go menu, Go to Folder, and paste in this text:
~/Library/Application Support/SketchUp 2021/SketchUp
In that folder, rename Plugins to be anything else. Open SketchUp and try the export again.
If it still crashes, go back into that folder and delete the new Plugins folder, and rename the old folder back to be Plugins again.
If it doesn’t crash, then one or more of your extensions are having an issue running under 2021. You should run Fredo6’s update option, to see if he has updated his extensions to be more compatible with 2021.1.