Look through the disclosures and agreements you signed on account opening and find out which banks PayPal is using for your account. The linked one above is for a deposit account at Synchrony Bank.
Do you have a PayPal account? If so, I assure you that you signed an agreement. The complaint in this class action lawsuit says that the agreement is a 65-page PDF. You would likely have signed it electronically by clicking an “I agree” checkbox.
If PayPal isn’t holding deposits and doesn’t forward the hold to the underlying bank, then go get your funds from the underlying bank or sue them.
FinTech is a stack of companies operating as veneers on the underlying, heavily regulated banks.