With InDesign 21.0, my plugin can no longer access files in the plugin folder when using the standard file uri scheme: file:///pathToFile (3 slashes).

Error: Could not find an entry of 'file:///Users/<user name>/Library/Application%2520Support/Adobe/UXP/Plugins/External/9e463c3edemo1.2.2/assets/files/main.css'

I use:

uxp.storage.localFileSystem.createEntryWithUrl(url.href, {
"type": types.file
})

It works:
- in 2024 and 2025
- when loading the plugin via the Adobe UXP Developer Tool
- with file:/pathToFile (just 1 slash)

It doesn't work:
- when installed (via double-click).

Is this a bug, or does it mean we can no longer use the standard URI (https://en.wikipedia.org/wiki/File_URI_scheme)?