Barney Frank straight up says as much: https://twitter.com/nic__carter/status/1635328056234766337?s....
Edit: FWIW, I have no insider knowledge of what was happening at Signature, but there's no one I've talked to in Crypto who was aware of risk at that bank. This is quite in contrast to Silvergate where it was well known that the bank was not healthy.
I was not a signature customer, but at Silvergate, even things as simple as changing an authorized user on an account took months or years to complete. I'm still an authorized user on an account at Silvergate that I haven't worked at in ~4 years (despite many, many customer service requests to be removed including repeatedly signed documents).
So much of why Silvergate failed was simply business execution.