Advice: Avoid paying via Zelle. At $Job, we are a long-time customer of one of the large banks which <i>owns</i> Zelle. Said bank told us to avoid paying for anything via Zelle, unless we had <i>very</i> clear & easy legal recourse in case of fraud. The did not quite say "Zelle is only a better payment solution if you are cheating people"...but they came fairly close.
Depends on the implementation. Initially used ACH for settlement and now they are moving towards RTP. (<a href="https://www.earlywarning.com/press-release/early-warning-services-clearing-house-enable-zelle-payments" rel="nofollow">https://www.earlywarning.com/press-release/early-warning-ser...</a>)