Blur effect in FCPX

I am surprised that FCP X 10.1.3 even runs in High Sierra.

That version of the application is ancient! It came out when the OS was at 10.8 Mountain Lion.

You can update your FCP X up to, I believe, 10.4 if you are running High Sierra.

You are missing out on years of updates.

You can download the updated version from the App Store. That is the only legal source for the software.

Login with the Apple Id used to purchase, and update. You will get the latest that works on your OS.

Before you upgrade your OS, make sure to have a solid backup.

I don't think you mentioned which mac you have, so I don't know if it can be upgraded to Mojave or Catalina.

Most macs since 2012 can, but you should have at least 4GB of RAM, and enough free space on your drive.

I am being cautious because all too often people upgrade without making a backup.

As Murphy's law has it, usually it is when there is no backup that things go wrong.

More often than not, upgrades go smoothly.

But I don't know anything about your software or workflows. Maybe you depend on some program that has not been updated to work on Catalina.

Backup, so you can revert, or install on a separate drive, and if anything goes wrong you can easily go back to the point you were at before upgrading. That is the point.

I have never had to go back to a previous version, but YMMV.

Please give specific information so we can help.

What version of FCP X and macOS are you using?

What do you see that is not correct? If possible post screenshots.

Your mac can be upgraded to Catalina.

Make sure you have a solid backup.

Alternatively, you may install Catalina on an external drive and test before you commit to installing on your main drive.