Latest Lightroom Classic crashes on upstart

Try resetting your Lightroom preferences:
https://helpx.adobe.com/lightroom-classic/help/setting-preferences-lightroom.html
Also see: https://community.adobe.com/t5/lightroom-classic-discussions/important-steps-for-manually-resetting-preferences-omitted-from-help-article/td-p/12972518

Quit Lightroom Classic.
macOS: Press and hold the Shift + Option keys.
Windows: Press and hold the Shift + Alt keys.
While holding down the keys, launch Lightroom Classic.
When asked, select "Yes". 

If that doesn't work:

Try logging into another Mac user account (you should make a new one); still crashing? 
Try starting up in Safe mode (hold down Shift Key when booting*), still crashing? 
You might want to try running a free utility like Onyx: still crashing? 
https://www.titanium-software.fr/en/onyx.html
Also view:
https://www.macworld.com/article/352902/onyx-review-macos.html
https://www.macworld.com/article/224955/how-to-reset-a-macs-nvram-pram-and-smc.html
From Adobe:
https://helpx.adobe.com/photoshop/kb/basic-troubleshooting.html

* How to start your M1/M2 Mac in Safe Mode
On your Mac, choose Apple menu () > Shut Down.
After your Mac shuts down, wait 10 seconds.
Press and hold the power button until the startup disks and Options appear.
Press and hold the Shift key, then click Continue in Safe Mode.