I suspect the only inbound connection you got is coming from Electrs, you can verify it using bitcoin-cli getpeerinfo and search "subver": "electrs",

At least, that is the issue I also encounter on my Raspibolt node, which I suppose Umbrel does only run over Tor connection. It usually happens because I got a bad internet connection, and it is usually fixed by just restarting the Tor service. After that, I leave it half an hour or just a couple of hours, and then the node usually got the inbound connections back.

I don't know for sure about your node, but you can also try to restart the Tor service if you want: