[BUG] thumbnails simply don't work

[nexy7574]

Describe the bug
Thumbnails generated for videos end up in some nested mess and in the end usually don't even display, and sometimes even break clients with strict spec adherence.

To Reproduce
Send a VideoAttachment with an auto generated thumbnail

Expected behavior
Thumbnail generates and is attached properly

[fd1f]

{
  "content": {
    "body": "tmpc2s89674.mp4",
    "filename": "tmpc2s89674.mp4",
    "info": {
      "duration": 20501,
      "h": 1080,
      "mimetype": "video/mp4",
      "size": 13203091,
      "thumbnail_info": {
        "h": 1080,
        "mimetype": "image/webp",
        "size": 5952,
        "thumbnail_info": {
          "h": 240,
          "mimetype": "image/webp",
          "size": 1212,
          "w": 135
        },
        "thumbnail_url": null,
        "w": 608,
        "xyz.amorgan.blurhash": "LTF=:axtofof_NayRjRktSoejZj["
      },
      "thumbnail_url": null,
      "w": 608
    },
    "m.new_content": {
      "body": "tmpc2s89674.mp4",
      "filename": "tmpc2s89674.mp4",
      "info": {
        "duration": 20501,
        "h": 1080,
        "mimetype": "video/mp4",
        "size": 13203091,
        "thumbnail_info": {
          "h": 1080,
          "mimetype": "image/webp",
          "size": 5952,
          "thumbnail_info": {
            "h": 240,
            "mimetype": "image/webp",
            "size": 1212,
            "w": 135
          },
          "thumbnail_url": null,
          "w": 608,
          "xyz.amorgan.blurhash": "LTF=:axtofof_NayRjRktSoejZj["
        },
        "thumbnail_url": null,
        "w": 608
      },
      "msgtype": "m.video",
      "url": null
    },
    "m.relates_to": {
      "event_id": "$3CVo0zEF7tAHHKNtFW2lk5kU5nFfRnVVFJiZau4v5qU",
      "m.rel_type": "m.replace"
    },
    "msgtype": "m.video",
    "url": null
  },
  "event_id": "$XFQNi6EeG6PkfaIw_eLvxrDC2-0eMkpy_C3IPlhdmTA",
  "origin_server_ts": 1737344170458,
  "sender": "@nonsensebot:nexy7574.co.uk",
  "type": "m.room.message",
  "unsigned": {
    "age": 1608
  },
  "room_id": "!general-v2:nexy7574.co.uk"
}

[nexy7574]

Danke

[nexy7574]

Should have been fixed in c1fbfc3, just needs some testing for confirmation