You may need to go through your plugins folder, and remove all non standard items, then add back in others, until you get the crash again.
For Mac the extensions, most are in this folder:
~/Library/Application Support/SketchUp 2020/SketchUp/Plugins
Some may be here:
/Library/Application Support/SketchUp 2020/SketchUp/Plugins
You can go into Finder, and use the Go menu, Go to Folder, then paste in the text I gave.
If you want, you could tell us some of the extension you’re using, and one of them may stand out as being not compatible with 2020.