Unable to upload images nor profile pictures on Desktop client and browser

So I've been having issues with uploading or changing profile pictures, no matter the size. When I upload an image, it gets stuck at 20% and then fails the upload, same goes with profile picture, except with no error message.

This issue seems to be persistent and tied to either Discord or my network since I tried uploading/changing profile pictures with VPN and it worked, and it also worked on mobile.

My suspicion is it's either my LAN or NextDNS configuration, but my phone has the same DNS configuration as my desktop, yet it worked. This issue has been going on for a few months now and came out of nowhere.

The strange thing is, the issue will only exist if I open the app for a long time; i.e The upload will only work after a recent reboot then it stops working until the next reboot.

I have tried everything to solve the issue: such as reinstalling Discord and even my OS (fresh installation) to no avail. I have formatted the os and uninstalled other suspected apps like Portmaster that has NextDNS configuration, but the issue still persists. I have checked with my NextDNS and no domain was blocked, at least the ones from Discord that is. I also have scanned my PC in case of malware but no suspicious app/file was found.

I have to see if the upload works with other file types, and if that's the case, it could be the images themselves, but why would they work on mobile but not Discord client/browser? They're the same image.