This issue occurs after rebinding the default key "F" to something else and it removes the keybind for zipline boosting.
There is no option to rebind zipline boost in the keybinds.
I also could not bind a variable to rebind it in the console as well.
Аcceleration and parry buttons are on the same button. So, if you want to change the acceleration setting on the zip line, you'll need to do it by changing the band, like in the picture.
Good day