@loa Are you sure that’s an Ad? Also, Brave doesn’t block 1st party Ad on websites. And you can try something interesting- Right click on the image > Go to Brave > Block element > Select area > Create. This will block that image from the site.
To remove the blocked element, you can go to brave://adblock/, scroll down to Custom filters and clear entry of related site. Tagging @Mattches for an insight.