Troubleshooting Tailscale and Bonjour / iTunes WiFi Sync

iTunes on Windows has a function known as iTunes WiFi Sync that allows iOS devices to talk to iTunes on the local network over WiFi for transferring files, making backups, and so on. In my limited understanding, this feature depends on mDNS/Bonjour to function.

I have noticed that when Tailscale is running on my Windows machine, WiFi Sync tends to silently stop working. Quitting Tailscale tends to fix it (and, if that fails to work, additionally restarting the Bonjour service).

What I do not understand is why this behaviour occurs; Tailscale blocks all multicast traffic, but why would it make mDNS fail on the non-VPN connections?

(Additional details: “Use Tailscale DNS settings” and “Use Tailscale subnets” are turned off on the Windows PC. My iOS devices are also Tailscale clients, but the VPN connections are almost always turned off due to battery drain issues.)

I would appreciate any help to further troubleshoot the root cause of this issue.