That's not just Coinbase. It's every neobank type app or service. The problem is that they can't handle the large volume of users while also dealing with fraud

That's not just Coinbase. It's every neobank type app or service. The problem is that they can't handle the large volume of users while also dealing with fraud & law compliance. So they basically have fraud detection algos that flag anything remotely suspicious with many false positives and they don't have the support staff to deal with the aftermath.