But regular American bank accounts are pretty different from PayPal or European bank accounts. (The original poster is talking about Chase so I assume the account in question was a regular checking account.)

I lived in the US for a couple of years, and the oddities of banking were a bit of a shock to me. In Europe we're used to bank transfers just working and costing nothing, but there isn't really an equivalent in the American system at all!

You can send a "wire" which usually costs $15-30 depending on the bank, and is meant for larger amounts and business transactions. Or, there's something called ACH which you can use to pay bills and businesses can use to send you money (e.g. paycheck deposits), but ordinary banking customers can't use ACH to send money to each other.

To address this obvious deficiency, banks have cooked up their own system called Zelle which is like a weird proprietary hybrid of PayPal and a European-style bank transfer. (Apparently it's so confusing to US bank customers that Zelle is widely used by fraudsters.)

So, when the OP wrote that they've been receiving deposits in the account that was closed, I'm curious to know what kind of deposits those were. Wires? ACH from businesses? Zelle? This could be a major factor in why the account triggered a red light at the compliance department.