I upgraded my Syncthing "server"/central peer to 1.23.6 (Linux/docker) and it broke resharing an untrusted folder.

Peer A shares a folder with Server. Peer A considers Server as untrusted. The folder is shared encrypted.
Peer B also shares that same folder with Server. It also considers Server as untrusted.

After updating, syncthing on Server says "Folder <id> (<name>) is shared in trusted mode with untrusted device <Peer B>; unsharing".

Downgrading to 1.23.5 fixes it. I also re-upgraded and it broke again, so it seems likely to be a regression.