Last year, Windows apparently started to write a small file to every USB stick that is plugged into an operating Windows computer. This changes every ISO with which you want to install Qubes on a computer running Windows. The built-in check before installation correctly returns an error.
I used a stick created in Linux to run Linux Mint from the stick and then installed Qubes in Linux Mint.
If the computer was last used with Windows. When the stick with the Qubes ISO is inserted into the computer and the UEFI is called at boot time, the file is already written to the stick. This means that the ISO is corrupted.
Please adapt the operating instructions if you notice the same thing.
It’s already covered in the installation guide:
Note: Using Rufus to create the installation medium means that you won’t be able to choose the “Test this media and install Qubes OS” option mentioned in the example below. Instead, choose the “Install Qubes OS” option.