Can you show us the issue? I'm not able to replicate the issue. see screenshot Did you try Firefox in Safe Mode? https://support.mozilla.org/en-US/kb/diagnose-firefox-issues-using-troubleshoot-mode#w_how-to-start-firefox-in-4troubleshoot-modesf5safe-modesf

I am having the same problem of not seeing the Amazon homepage properly and also not being able to browse through their products. When I try to browse, the page turns all black. I turned off Enhanced Protection for Amazon and it worked briefly but still had weird text and image issues but was able to browse. Then the site reverted back to the same problem. Unfortunately, I have had to use Chrome to purchase products on Amazon for the past week because I keep getting black pages on Firefox for Amazon products.