that the wallet will show you a new address every time the previous one gets funds in it. previous addresses continue to work though. also, for monero this behavior is not necessary. not sure if that's a new setting or something, but in any case, safe to ignore.

It gives you a new receive address every time. When/if ever QC could break this specific privacy assumption in the future (Monero is built on modular privacy assumptions some already QC "secure") then it still means with coin control your receipts/spends are not linkable.

This is so you don't link different identities and activities together that you may not want connected. If you use the same address everywhere it's pretty obvious that you're the same person. But for payment targets on your public profile it doesn't matter