If you only have 2 wires at the switch, neither is a neutral. One is the “Line” which is the hot from the breaker, most likely the black one; the other is the “Load” to the light fixture which is hot only when the switch circuit is closed, most likely the white one. If the house was wired with a neutral circuit, required for new construction in the early 80s, there would be a third wire, usually tagged, but commonly white.
The Wyze Switch requires a Neutral wire because it requires power thru the switch at all times to keep the WiFi and chipset board alive 24\7. It does this by routing a small amount of current from the Hot Line to the Neutral to keep its brain alive. Only when the switch is on and the Fixture Load Circuit is closed does it send full power to the fixture.
If you hooked the Wyze Switch up with the white in the Neutral, it was only sending a very small amount of power to the Floodlight, just enough to keep the switch alive. Full power has to come out of the Load hookup on the switch.