Share banner seems to be not working

[madduck]

Description
No matter what I enter into the banner field (I tried absolute and relative URLs, as well as HTML as suggested here, the banner always seems to be an image, with the image source an API call that yields a 404:

Expected behaviour
I'd love for the banner to be shown like I entered it ;)

What is happening instead?
Instead, it looks like this:

[madduck]

I just found this in the logs when using HTML:

filebrowser_1  | 2026/03/11 10:44:01 [ERROR] public share handler: error processing filelist: [<img src="https://www.toni-kg.de/wp-content/uploads/2024/10/ToniPark22.6-31-scaled.jpg" width="200"><br/><strong>Confidential Files</strong>] with error could not stat path: /test/foo/<img src="https:/www.toni-kg.de/wp-content/uploads/2024/10/ToniPark22.6-31-scaled.jpg" width="200"><br/><strong>Confidential Files</strong>, lstat /test/foo/<img src="https:/www.toni-kg.de/wp-content/uploads/2024/10/ToniPark22.6-31-scaled.jpg" width="200"><br/><strong>Confidential Files</strong>: no such file or directory

And if I use a URL or relative path to a local asset (/banner.jpg in this case, which I made available in the share):

filebrowser_1  | 2026/03/11 11:52:25 [ERROR] error accessing share asset: source= path= error=path not provided
filebrowser_1  | 2026/03/11 11:52:25 GET     | 404 | 192.168.235.1:59570 | N/A          | 0ms          | "/public/api/share/image?banner=true&hash=t1-kV9uu-y6CZ7g_3mzO-Q"

The only way to make it work is by specifying source=test&path=%2Ffoo%2Fbanner.jpg, but I'd actually prefer to use an absolute/external URL.

Note: favicon external URL works.

[madduck]

Note: this is also present in beta.