You're suggesting this likely happens because the payment processor has reported their suspicions to a regulator who isn't getting back to them in a timely manner, and so they can't release the funds until they do? I'm a bit confused because it seems to me that the tip off is when they won't disburse your funds.
ETA: Maybe it's more that they can't give you any information because they can't allow adversaries to differentiate between glitches, random screenings, and investigations?
If a payment processor suspects a business is laundering money, they can hold the funds, but it's illegal for the payment processor to tell the business that they suspect money laundering. So they end up saying something like "we're holding your funds for vague unspecified reasons".
(Disclaimer: Used to work at Stripe, but not on this particular area. Not an expert on either the law or Stripe's policies.)
Add in the fact there are people trying very hard all the time to defraud the payment processor.
So now you can directly measure false negatives in fraud detection, but your false positive rate is harder to figure out. And whatever mechanism you use to recover from false positives can be abused by true fraudsters.
So it becomes a hard problem - but it is a problem which customers of the payment processor are paying them to solve. So it’s definitely reasonable to expect better.
1: I think a reasonable-ish definition of tipping off: https://onlinelibrary.wiley.com/doi/10.1002/9780470685280.ch...