Ya know what, fair. That's a more sensitive risk profile than I operate under and Zelle is 3rd party to my bank but if you bank with one of the major national banks I can see that providing some comfort.
It's not actually that sensitive a risk profile -- Paypal has shown itself to be untrustworthy with how it'll just freeze an account that you have a bunch of money in or explicitly suck extra money out of your bank account or with the updated terms of service last year that they "backed down on" only slightly. Paypal also owns Venmo, so I won't touch that one. Not sure about CashApp, but I only see it listed by sketchy people and instagram influencers, so I've never considered it trustworthy to begin with. At least Zelle was part of the services provided by my bank (Chase)? Clearly it's worse than that initial impression in practice, but I'm not sure that it's really worse than Paypal or CashApp?
Zelle is not exactly 3rd party since it is operated by a company that all the big banks themselves own (and assuming you have an account at one of the big banks):
