Sorry, bad news, but a single-channel forwarder is not a gateway. And the other users now have their packets received and forwarded to TTN by a device that claims to be a gateway, but really is not, which can harm their operations. As clearly other TTN users are in your (long range) neighbourhood (though maybe they’ve not made their gateway’s location public), please disconnect your single-channel forwarder from TTN.
See also Single Channel Packet Forwarders (SCPF) are obsolete and not supported.