mobile data do not work.
Manjaro Phosh an PM phosh do its work.
2 weeks ago I updated Quectels firmware to 0.6.4
Maybe an error message will give you a hint. It appears when trying to establish a Nextcloud connection.
SIM PIN unlock required. The mobile broadband device 'Quectel Incorporated LTE Module' requires a SIM PIN code before it can be used.
The Quectel modem works with pmOS Plasma, so it could be a problem in Manjaro-ARM-plasma-mobile-pinephone.