What is the black small squar things for? iPhone12 on magsafe?

Hi,man.
I saw your question.
2nd 12 housing maybe have not magsafe. it's tape.
Originally, 12 housing have Qi coile. it support mag safe.
your first replemane housing have coile,I think.
I recommend you don't replace new one.If you want to replacement storongly, you should buy from a reputable supplier.

And your another question
when you hear noise during recording or after recording.
you use original parts or replace it?
if you use not original parts,maybe it broken.
Buy a new one,please.

Thank your question,have a good day.