Please explain the problem in detail. What happens? What are the exact error messages?

Make sure you are not blocking content.

https://support.mozilla.org/en-US/kb/enhanced-tracking-protection-firefox-desktop also see https://blog.mozilla.org/security/2021/03/23/introducing-smartblock/

https://support.mozilla.org/en-US/kb/smartblock-enhanced-tracking-protection

Diagnose Firefox issues using Troubleshoot(Safe) Mode {web link}

A small dialog should appear. Click Start In Troubleshoot(Safe) Mode (not Refresh). Is the problem still there?

Many site issues can be caused by corrupt cookies or cache.

Warning ! ! This will log you out of sites you're logged in to. You may also lose any settings for that website.

• Delete cookies to remove the information websites have stored on your computer {web link}

• How to clear the Firefox cache {web link}

The login page of this site is not displayed but in another browser is displayed easily. https://app.setareyek.ir/login

I have several versions of Firefox. The web page displays, but as it is not in English, I can't tell if there is a problem.

Use these links to create a new profile. Use this new profile as is. Is the problem still there?

https://support.mozilla.org/en-US/kb/how-run-firefox-when-profile-missing-inaccessible

http://kb.mozillazine.org/Profile_folder_-_Firefox#Navigating_to_the_profile_folder

https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles

https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles

Type about:profiles<enter> in the address box.

yes ,problem still there; This site is a Web Application version , Is there any specific settings?

In the Edge browser, an extension is installed after entering the site address. And then the login page is loaded. I also sent pictures to you. But in Mozilla, nothing happens

picture 2

I called for more help.

Web applications do not work in Firefox for desktop. In Firefox for mobile I get the login page as shows in your last screenshot.

There is no way?