Background image upload fails with "413 Content Too Large" #1487

Hi, I’m trying to customize Heimdall by using a background image, but I’m running into a problem.

When I upload or set a background image, if the file is a bit large, Heimdall throws the following error:

Oops! An Error Occurred The server returned a "413 Content Too Large". Something is broken. Please let us know what you were doing when this error occurred. We will fix it as soon as possible. Sorry for any inconvenience caused.

Expected behavior as a user:
The application should either:

1. Allow larger background images, or
2. Provide clear guidance on the maximum file size allowed.

Environment:

running latest docker image (lscr.io/linuxserver/heimdall:latest)
smallest image size that threw the error: 8.688 KB