User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:74.0) Gecko/20100101 Firefox/74.0

Steps to reproduce:

tried with safe-Mode still no go :(
https://www.theathletesfoot.com.au/shop/new-balance/gender-mens

Actual results:

something just tries to Load the page but doesnt
https://www.theathletesfoot.com.au/shop/new-balance/gender-mens

Expected results:

should be able to click on the Shoe to display it on a page before buying it online

Confirmed on Win10 x64 with today's Nightly. Setting to New

I can reproduce the issue(dimmed and forever spinning loading indicator in the page)
STR

1. Open https://www.theathletesfoot.com.au/shop/new-balance/gender-mens
2. Wait for tab loading indicator stop, and allow geo location request
3. Click one of thumbnail. And wait for tab loading indicator stop
4. Back to previous page. And wait for tab loading indicator stop
5. Scroll up and down and/or reload

Actual Results:
Page dimmed and loading indicator in the page is spinning forever.
Unable click on any clickable element in the page.

Expected results:
Every thing normal

Regression window:
https://hg.mozilla.org/integration/mozilla-inbound/pushloghtml?fromchange=d19cffeae1febc6d669a024340de25228e544475&tochange=24d97dc514d4b8fe608e9aee7527615c1e613606

Console error:

 TypeError: xhr.responseJSON is undefined     static.min.js line 10 > Function:6:711