The "what is a bank" question is complicated, so "fintechs" have been operating in areas that are in some gray areas in between "definitely a bank" versus "definitely not a bank."
At the most informal, you've got things like a roommate who collects everyone's fair share of rent before sending one payment to the landlord, or a parent who keeps track of their kids' virtual balances of what the kids are allowed to spend. These definitely aren't banks.
Then you've got things like short term balances between people who deal with each other: an employer who keeps track of hours and pays the employee at the end of the pay period, a retail customer who has some store credit from a returned item, a contractor who periodically invoices a customer for work performed, etc. Despite the "credit" and "balances," these aren't bank accounts.
Some gray areas get a little bit more complicated. You have airline mileage and hotel point programs where the miles/points can be used to purchase goods and services, including sometimes those not even being offered by the business where the miles were accumulated.
Then you get into banking-like structures that might be, or might not be banks. Is it banking when you buy something on a periodic payment plan? What about when you put down a deposit to reserve a preorder for something you expect to buy when that product is released? Or give someone a gift card for a specific store? Does it matter if these programs are administered by third parties separate from the buyer or seller?
Even things like Apple Cash or PayPal or Venmo or CashApp perform functions that can be bank-like, or not really bank-like.
Fintechs have looked at the constantly updated rules of what they can or can't do before needing to comply with certain banking regulations, and usually try to avoid accidentally triggering certain rules. And the rules don't divide into just bank versus not bank, as many of the rules apply to non-banks that do certain things, and many of the rules don't apply to even banks that stay out of certain product lines. So it's not a binary yes or no, but a series of complicated areas where some are yes and some are no.
The big problem, where this Synapse bankruptcy is hurting people, is when people worked with an entity that provides certain services, who relied on the back end on a middleman that provides other services, and then the middleman fails. People operating in the gray areas are exposing themselves to systemic risks they might not fully understand.
