DC AC Inverter topologies
The transformer size is slightly larger for centre tapped (because slightly more copper is needed in the transformer primary)
In a teardown video they show the 120V version of this inverter with two large MOSFETs on a heatsink, so probably a centre tapped transformer.
In a compact inverter like this one the transformer probably runs at a high frequency to produce a high DC voltage that is then chopped to make AC at 50Hz.