Is Docker starting up and one of the containers mounts a volume to a /storage folder on the host? That could explain it but I’m not super clear on all that’s going on in your system.
Quick test: disable auto start on all your containers and restart and see if it recurs.
Take a look at the Linuxserver Docker images. They curate a huge list of self hosted apps that is great to browse and look for ideas. You don’t need to run Docker and use their images - I’m just suggesting review their list of apps they support to get some ideas of what’s out there.
That Pi is too old to handle any media tasks (like running a Jellyfin server), but for any low intensity duties it’s still perfectly usable.
So is the issue that your extra drive mounts to /storage, but that happens after Docker has already started and taken over the directory, so the mount fails? Normally I’d expect it to happen in the other order. Is this a weird race condition?
This might be a good thing to run through with ChatGPT- there are probably ways to delay the Docker container start, but maybe there’s a more significant misconfiguration you can deal with.