Have you tried starting in Safe Mode?

Jeremy Sanders said

Have you tried starting in Safe Mode?

Yes. The same thing happens when I try starting in safe mode. The crash report ID I gave is from when I tried starting in safe mode.

Start Firefox in the terminal and see the report.

JohannHan said

Start Firefox in the terminal and see the report.

It doesn't seem to crash if I just run firefox with no parameters. If I run firefox %u like it is in the .desktop it gives the same behavior as I described in the original post. Here is a crash report when running firefox %u from the terminal bp-fb3f718a-3fc8-4c93-a253-686aa0190810. I assume that just deleting the %u from the .desktop file would solve the problem but I don't know if this would have any other unintended consequences. Also I would have to redo this every time firefox updates.

I don't know if this information helps, but I'm using the Gnome desktop. I tried disabling my gnome extensions but that didn't help the crashing either. Interestingly I tried another desktop (cinnamon) and did not get any crashing. Gnome cannot be the problem though because my other computer is running gnome also with no problems with firefox. I would really like to get this problem fixed.

In case anyone comes across this in the future, updating to firefox 69 fixed the problem.