403 when trying to use custom background

[LokeYourC3PH]

Describe the bug
When I try to upload custom images or files to be used as a background on the login page, it does not work unless I modify the default "bg1.jpg" file. Any other file when loaded represents the following in my console:

To Reproduce
Steps to reproduce the behavior:

1. Go to login page.
2. Get 403 error in console.

Expected behavior
For images/videos to be loaded.

Screenshots
Posted above.

OpenWRT:

• Version: OpenWRT SNAPSHOT r24072-a181b9f0f9
• Theme: Argon
• Version: 2.3.1

Desktop (please complete the following information):

• OS: Windows 11 Pro
• Browser: Firefox
• Version: 118.0.2

Additional context
I would assume this might stem from the fact that I use HTTPS mode for LuCI, but can't confirm whether this is 100% the case.

[LokeYourC3PH]

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