We are definitely not dropping support for Zerotier. Zerotier will be updated in due course. Additionally, Tailscale also works behind CGNAT, providing VPN options that do not require a static IP. We acknowledge the need for an updated Zerotier package and will consider this for future firmware versions.
It does seem like ZeroTier support might be lagging behind compared to other VPN options. Consider reaching out directly to Teltonika support for clarification on their plans for ZeroTier updates.