I had a hard time seeing images with Firefox - not all the time, but enough of the time I had to open Chrome up to see images.
But I hate Chrome, so finally ditched FF and use Brave exclusively. Has built in security features including ad blocker.
I suspect that you were wise to dump Chrome. I know nothing about Brave. What operating system are you using? I have never {with my last few operating systems - Win 7, 8 & 10} used any other browser than FireFox and have never had any trouble with images. I wonder if some other browser that you used with your operating system put some malicious malware on your computer to thwart FireFox... a bit above my pay grade.