"This addon could not be installed because it appears to be corrupt" Firefox Developer Edition

I already set xpinstall.signatures.required to false. The extension loads fine in about:debugging but not in about:addons (where it matters). The error persists regardless of whether I add the activeTab, tabs, or <all_urls> permissions. Using Firefox Developer Edition 109.0b3 (64-bit).

Manifest:

{
  "manifest_version": 2,
  "name": "My Extension",
  "description": "Description of my extension",
  "version": "1.0",
  "icons": {
    "48": "icon.png"
  },
  "content_scripts": [
    {
      "matches": ["<all_urls>"],
      "js": ["content-script.js"]
    }
  ],
  "web_accessible_resources": [
    "web-accessible-resource.html"
  ]
}

Zipped extension:

extension.zip
├ content-script.js
├ icon.png
├ manifest.json
└ web-accessible-resource.html

Thanks in advance for any help.

It appears that you miss an "applications": { "gecko": { "id": "X@Y" } } at the end of your manifest.json (see also https://github.com/puemos/hls-downloader/issues/285)