I have two phones.
One "privacy aware" phone (lets call it PA-Phone) with custom rom and without google services but with SIM card and LTE,
and one "No privacy" phone (lets call it NP-Phone) that has google services and some necessary apps for work and chat apps for friends that don't want to move over to more privacy focused chat applications. The NP-Phone is mostly off, except when I need to do some work or contact a friend and then I connect it to the work or home wifi.
Anyway, sometimes I find myself in a situation where I need to turn my PA-Phone on as a Tethering Wifi Hotspot, to which I connect my NP-Phone.
In such scenario, if browsing the web, or using non-privacy focused apps on the NP-Phone, what data about my PA-Phone will be known to the endpoints/servers that I connect to?