Did you try to reboot the watch? I assume this would fix it.

iirc the display engines are built into the AXX chipsets. As only pro phones get a pro chip, Apple probably does not add the capabilities to drive displays at higher refresh rates to the non-pro silicon. So even if the display itself could go higher, the hardware to drive it is missing, not locked in software.

It‘s good to call out on Apple for delivering subpar displays in a „premium“ product. The non-pro phones being 60Hz only in 2024 just to upsell to the pro phones is ridiculous.