What’s the most recent known speciation event?
— Misha Gurevich. Angel Investor, Photographer. (@drethelin) July 19, 2021
This exhibits a fundamental misunderstanding both of biology and evolution. Speciation is not an event, it is a process. Species boundaries are not so sharply-delineated as that, there is not one identifiable moment when one species diverges into two.
I don’t know why people think about this sort of thing — and most things — so poorly.
Nevertheless, there is some literature.