There is security software like Avast, Kaspersky, BitDefender and ESET that intercept secure connection certificates and send their own.

https://support.mozilla.org/en-US/kb/firefox-cant-load-websites-other-browsers-can

https://support.mozilla.org/en-US/kb/firefox-and-other-browsers-cant-load-websites

https://support.mozilla.org/en-US/kb/secure-connection-failed-error-message

https://support.mozilla.org/en-US/kb/connection-untrusted-error-message

Websites don't load - troubleshoot and fix error messages

http://kb.mozillazine.org/Error_loading_websites

What do the security warning codes mean

Sorry for the late response, but none of these responses were successful in solving the issue. I am not using any antivirus right now except Windows Defender, and it's also not an internet provider issue as the issue still persists after I moved into a new apartment with a different provider.

I attempted changing network.dns.disable to true, I tried changing dns prefetch to true, and I cleared the dns cache. I also changed the proxy from using system settings to using no proxy, but that also didn't affect anything. At this point I believe it's a problem with firefox somehow failing to load the javascript on the cached page due to the Cross-Origin Request Blocked errors, but I'm not sure what private browsing is doing differently with cookies and the cached page that allows it to work fine there.

Using this extension (https://addons.mozilla.org/en-US/firefox/addon/cross-domain-cors/) I tried to add a-v2.sndcdn.com and force the CORS requests to go through, but this still didn't work.

Thanks

https://support.mozilla.org/en-US/kb/update-firefox-latest-version?cache=no Did you update Firefox to the latest version?

Version 91.0.2, first offered to Release channel users on August 24, 2021

Just updated, still doesn't have seem to done anything.

One interesting thing is that I seem to have found specifically what is causing the website to not work. Going to about:debugging and unregistering the soundcloud.com/service-worker.js makes the site work again, but then as soon as I refresh the site the worker comes back and then the website doesn't work anymore. I'm not sure if this is a problem with Firefox anymore, or if it's just a problem with Soundcloud's javascript code. Although, it's probably not a problem on Soundcloud's end given that it works in private browsing and on other's browsers just fine.

One interesting thing is that I seem to have found specifically what is causing the website to not work. Going to about:debugging and unregistering the soundcloud.com/service-worker.js makes the site work again, but then as soon as I refresh the site the worker comes back and then the website doesn't work anymore.

You should contact support for that website.

A temporary solution has been found!

By using this extension https://addons.mozilla.org/en-US/firefox/addon/cors-unblock/ I was able to force CORS connections and after clearing cache the site loads.

Still no idea why it works fine in private browsing.

EDIT: nvm, CORS requests are still blocked once the page reloads or is visited again. Problem is also now happening on https://discord.js.org/#/docs/main/stable/general/welcome