Browser keeps crashing

then in terminal propably you must put a command umount -f /media/dev/sdc

When you umount that usb then you can format with cfdisk or gparted.
On gparted you have also option umount.

It says it is not mounted.

when you go on gear you can choose option repair a disk then format on some ntfs or fat.
This is bootable this is live ISO where you cannot propably delete that partition.
This is core.
You cannot delete a pendrive with linux live when you using that pendrive.

This propably help.

You must format that pendrive from another pc or another pendrive with live linux.
You cannot full format your pendrive and the same time using that pendrive with live linux.

OK i think we need to get back to basic's,
Extra ram/swap shouldn't be needed.

There's an underlining problem.

First VM = Virtual Machine, these can have huge ram usage.

here is a photo of 20 diff tab's open in firefox.

Here's firefox opened 20 times.

Can you please screenshot your monitor without Brave open & with brave Open.
And display here ty.

Ok, close down the Disks application. We're going to brute-force it.

Start Terminal, and enter:
sudo dd if=/dev/zero of=/dev/sdc status=progress

From your image, we know that's /dev/sdc, so we'll just use dd to zero the entire drive. That'll wipe that partition off the drive.

Once that's done, then you can follow the instructions in #4 above to set it up as a swap drive.

Thing's that may have contributed to the issue.

New extension's, or failing extension.

Try removing each extension one by one until you may find the problem extension.

So, check and disable extensions, create a new user profile, etc. Finally, if nothing helps, you can reset the Brave browser to the factory defaults.