Are they Bluetooth headphones? If so, check the protocols supported by your phone, and by the headphones, e.g. aptX vs LDAC vs SBC. It’s possible that it’s not a “downgrade” on the new phone, but rather an upgrade to a better protocol, but unfortunately not one compatible with your headphones, so you end up using a low quality fallback.
You may also want to check your settings, and see if you can select a specific protocol. Sometimes a lesser protocol is chosen by default, if the better protocol uses more battery. This may be available to you in the phone settings, or as an option in an app for the headphones (e.g. my Anker Soundcore app allows choosing between two protocols).
I’ve personally lived in places where the closest convenience store was 2.25 km, and the grocery store was nearly 18km, as well as places where a convenience store was literally a part of my building, and grocery stores were walkable distances.
The U.S. is enormous and varied. Take a look at truesizeof and compare the U.S. and Europe (don’t forget to add Alaska and Hawaii - they won’t be included in the contiguous states). Consider how different London is from rural Romania.