Zerotier and Tailscale both use firewall settings which conflict with the current GL.iNet implementation of various firewall rules/policies. Supposedly Version 4.2 will support both ZT and TS, though there is no firm date for release on that. (There are commits in the code which suggest that work is happening, but nothing concrete yet). I have not tried ZT personally, but with TS the issues come into play when you try to use an exit node - otherwise it works ok ish.

Depending on what router you have you can install a stock (or more stock) version of OpenWrt, which functions fine with both ZT and TS.