Thanks for the information.
I'd like to work on this with you for a bit.
From the current Software Boutique you can install the current version of Brave. I'd like to try and see why your instance of Software Boutique isn't showing correctly. For reference I have just installed the current version of Brave from the Software Boutique.
I'd like to do a bit of troubleshooting with you if you'd be up for that.
I'd like you to run these commands:
sudo snap remove software-boutique ubuntu-mate-welcome
Then go to /home/<username>/snap
and do an ls -al
Then do an rm -rf ubuntu-mate-welcome
and if it exists and rm -rf software-boutique
Next please run sudo snap install ubuntu-mate-welcome --classic software-boutique --classic
At that point let's have you run the Software Boutique and see if you are running the correct version.