Are you 100% sure it was a form from a bank?
Everything stinks of a scammers phishing form, leading to scammer calls.

I expect the only time a bank is going to want your phone number is when you initially sign up with them. After that, they should know who you are and your contact details.

I almost got caught out by a “sorry we missed you” delivery message, until it was asking for my date of birth.
Some of these random emails and SMS can catch you off-guard and seem legit

No this was legit. This was a mortgage inquiry form on their website and one of their lone officers called me soon after

Banks’ system are probably already compromised and don’t even know it.