Thanks! I do have an external monitor and a bunch of plugins. Your suggestions helped, somehow after I disabled and enable all the plugins, I tried with a few papers, and the crash disappeared! Many thanks!
Yep, there's a known bug in Zotero where plugins that open a progress window can trigger a crash when external monitors are used on macOS. That will be fixed in Zotero 7 later this year.
Are you using an external monitor? Does it happen if you disable any third-party plugins?