ANT, and later ANT+, are wireless protocols used by various athletic training devices, I have a heart sensor using one and a rowing machine that reads it.
The protocol will end-of-life. Garmin (its creator) cites regulatory changes (I guess the US FCC Part 15 [Title 47 CFR Part 15] or its equivalent elsewhere). But there is also the fact that BLE (Bluetooth Low-Energy) has obsoleted it.
https://www.trainerroad.com/forum/t/ant-changes-ending/99373