My battery health still 88% although used since 2019 June.. Hehe

I just got iphone xs max from my wife after she upgraded to ip13. My previous iphone is 6 year old iphone 8 plus, and i think iOS17 will be the LAST update before it can’t be supported anymore. 

Here are few of my questions:

1. I understood this phone utilizes FaceID technology to unlock the phone. Very convinience indeed when i am INDOORS at my house/less people.
But i am unable to unlock when using face mask during outside. Saw a few youtube videos to “trick” the phone to allow face unlocking when putting on face mask, but got some comments saying, it will work 50-70% of the time, or it won’t work later afterwards. Is there any proper workaround to this? Only iphone 12 and above have the ability to unlock while wearing face mask am i right?

2. I also know we can unlock phone if we have apple watch. If i have apple watch SE, can i unlock even if i wear face mask? And will it also unlock related banking apps that need to use FaceID in the first place?

3. Already replaced the battery at Switch last week at RM380. Before this the battery health was at 83% after 4 years of usage. But still i find xs max is quite the battery juice guzzler, even on normal usage?

4. I aim to get iphone 15 when apple decided to put USB-C port, and they have iron out the green screen/white screen issue that has been plaguing 13/14 pro series due to imperfected 120Hz refresh rate technology. Funny my ipad pro M1 doesn’t have this green screen/white screen issue even though it’s using 120Hz. 

appreciate your feedback guys. Thanks!