This backports the commits from the upstream `stable-4.0` branch,
including the security content of
[4.2.6](https://github.com/mastodon/mastodon/releases/tag/v4.2.6).
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Co-authored-by: blah <blah@blah>
Co-authored-by: Emelia Smith <ThisIsMissEm@users.noreply.github.com>
Co-authored-by: Claire <claire.github-309c@sitedethib.com>
Misty De Méo