So I am currently testing the Q4.1-rc1 installer on multiple machines. I have noticed that when I set the main template to Fedora 34 during installation, the Fedora template applications are not available, and AppVMs that are based on Fedora 34 doesn’t have terminal, browser, etc…, in their respective menus. Here are some screenshots:
I think this is Qubes 4.1-RC1 fails to install fedora-34 template · Issue #6975 · QubesOS/qubes-issues · GitHub, or very similar issue.
Is it better when you click “Refresh Applications” button?
Fixed 
I simply did a successful update for Fedora 34. I had to restart the computer to pickup the changes. Restarting the AppVMs didn’t work at all.
The “refresh applications” button didn’t do the trick and resulted in a failed message. I don’t really remember but it was related to the template “Fedora 34”.
Please be aware that downgrading the default kernel in global settings to 5.10.61-1.fc32 resolved the DomX out of PdD memory! issue. Otherwise, I wouldn’t be able to update the Fedora template in the first place.