On the master branch version of the ATT&CK website, mobile ATT&CK Navigator links include the mobile domain twice: https://mitre-attack.github.io/attack-navigator/mobile/mobile/#layerURL=...

This occurs on both group and software pages:

https://attack.mitre.org/groups/G0070/
https://attack.mitre.org/software/S0329/

Since the template for the navigator links is the same across domains, likely the python code feeding the layer links to the template differs between enterprise and mobile.