mac crashes every night

... when I open it up in the morning it always says that it had to be restarted because of an issue.

What is the exact wording of that dialog box?

Refer to If your Mac restarted because of a problem - Apple Support.

Click the Report... button. Copy the text before sending it to Apple. You can paste that text in Pages, TextEdit, or here.

Yes. You can find them in its Sources column, under Crash Reports.

Or in the Finder:

~/Library/Logs/DiagnosticReports/

I believe that report just confirms what I already suspected: a GPU fault.

It's possible that it's a known fault that Apple might be able to address in a future macOS update. The reason for expressing such uncertainty is that it's literally impossible to know whether Apple is aware of that, so the answer is the same: Contact Support and ask them what you should do. They may or may not need to physically inspect the Mac.

That's all that can be determined.

There is only one culprit in that list, and it's the Mac's GPU. It implicates a hardware failure, so there's not need to examine its contents. Contact Support to determine repair options.

You can if you wish. The one you selected is as good as any of the others indicating a GPU restart.