I've formatted a USB after it was used for an iso with ventoy, and now the usb doesn't work.
Google says I have to clear the USB, create a primary partition and format it to fat32 (via diskpart) but I'm stuck with "no volume for this partition". "Create volume" doesn't help: it says the disk isn't dynamic
What should I do?

Update: I've abandoned rescuing the USB and just flashed another iso with balenaetcher, and it booted normally. According to my previous experience, the USB will be fine once formatted from this state.
But I would still like to know how to rescue dead USBs like in my case.
So, don't use ventoy unless you really understand what you are doing.

Context: it sounds like OP is probably using Windows; he mentions using diskpart, which is a Windows utility.

With situations like this, I’ve found it best to switch to another OS and try their disk format utility. Sometimes I’ve had this issue on Linux and fixed it on Windows, issue on Windows and fixed on Linux, issue on Windows and fixed on macOS, etc.

If you have another computer other than Windows, give it a shot. On Linux, try gparted and if on macOS, try Disk Utility.

Try formatting to any format and then try formatting to your desired format. You may find that it works that way.

If you're on Linux, just copy (or dd) /dev/zero to it for a few seconds to wipe the partition table.