FCP 10.6.4 Crashing in Monterey

Whenever the application crashes you should reset the preferences. Hold ⌥ ⌘ as you double click the library you want to open to launch the application. A dialog appears asking you if you want to Delete Preferences. If you don't do this while double-clicking your library, the application will open a default Untitled  library.  

Start with that and then see what happens. Test with a new admin user.

Let’s move onto here.

Post an EtreCheck report https://etrecheck.com giving the application Full Disk Access in Privacy System Preferences. Copy the report and use the Add Text button to paste the result into reply box. 

Many of your drives are full. They need to have a minimum of 10% free space, preferably 15%.

You have Google's keystone daemons and agents installed. They break the video toolbox. See https://chromeisbad.com for instructions on how to completely remove. Simply trashing Chrome.app is not enough. A reinstall of FCP is usually necessary.

You have very old, deprecated software like RealPlayer, Flip4Mac and Silverlight installed. This tells me you've been upgrading in place for many macOS upgrades. In my opinion, the best thing you can do for your Mac is to make two complete backups, then a clean OS install (which means reformatting the boot drive), then restore *ONLY* your User data from your backup (restoring everything just copies back all the cruft that is likely causing the problems), then download fresh copies of your software from the App Store and 3rd party developers.

If you want a preview of what our iMac could be like, do a fresh OS install on an external SSD, create a new user and download FCP from the App Store.

We can't do anything with a crash report. Post an EtreCheck report https://etrecheck.com giving the application Full Disk Access in Privacy System Preferences. Copy the report and use the Add Text button to paste the result into reply box. 

System security is disabled and you have installed the nefarious cleanmymac.

The first thing to do is to rectify that.

Never ever install any program that claims to clean, optimize or speed your mac.

I will look at the rest of the report but this needs to be fixed

You also have Chrome and its evil keystone daemons. They hog the system videotoolbox and cause serious problems to video applications.

See https://chromeisbad.com for an explanation and instructions for removal.

Hy, my fcpx also is crashing.

here you are.

I think maybe is some scripts in the mac.

Cause i was working fine and the fcpx goes to hangup, force to close, and never open again.

Can you download EtreCheck and post the complete report about the system.

Please heed the solid advice by terryb. The issues raised in the Etrecheck report need to be addressed.