Firefox Ability to Display my.nextdns.io Recently Broke

approximately 4~7 days ago, I noted FireFox (v56.0) no longer displays the above mentioned site, where-as months prior, it had no problems.

So.

Since NOTHING changes (by design) on my system, this proves NextDNS changed something that specifically prevents FF from using the site.

Note: the domain nextdns.io has, for those said months always & specifically been allowed to use Scripting as well as Cookies.

Also, the browser WaterFox Classic (v2021.02) does, currently display the site my.nextdns.io as FF used to.

Thus indicating (and of course, the lazy will take the following statement as further excuse to remain lazy) that the access to the site my.nextdns.io issue is not critical as it is still accessible and that one can continue to manage their Internet usage.

I would ask the changes made be reverted/corrected to allow one to continue to use FireFox.

Thank You.