I tried on both Brave and Tor browsers, but it didn't work the only link that works for me is if you change the link from HTTPs to HTTP after changing this to a non-secured protocol the onion link is accessible on both Browser Brave and Tor.
I have no idea why this happenes... but, however, as LV and Bitmaxz explained above, you should not worry about this. As long as you can access the website through one of the TOR links everything should be okay.
It's been almost a month, and my support ticket still hasn't been resolved.
Have you tried reaching them through SimpleX?