In LOOT's repository, run the scripts/generate_manifests.sh script (on Linux or in WSL).

Copy the JSON files it generates in build/flatpak-manifests to the manifests directory in this repository, replacing the existing files.

Copy the resources/linux/io.github.loot.loot.yml file from the LOOT repository to this repository.

In the copied YAML file, replace the LOOT module's dir source with a git source with the url of the LOOT Git repository and the relevant Git tag name.

E.g. replace the bit that looks like:

  - type: dir
    path: ../..
    skip:
      - .github
      - build

with something that looks like:

  - type: git
    url: https://github.com/loot/loot.git
    tag: 0.23.0

In the copied YAML file, replace all instances of ../../build/flatpak-manifests/ with manifests/.

Commit the changes.

Open a pull request for the changes.

Once Flathub has built a test version, test it out. If it works, merge the pull request.