Do the other gauges still work? Tachometer? Fuel gauge? No other lights coming on or going?
I had the road speed sensor go bad on one of my bikes. It would display normally, then drop to zero for a few miles, then work again. Ultimately that was the sensor.
You have to drop the exhaust and dig into the faux oil tank on the right side of the bike to replace it. Once all that’s off there’s one screw and one plug to swap it out.
With that said: I don’t know if you have any other history with the bike like rodent or fire damage to the harness. Obviously: those should be looked at first. If the harness looks good, the sensor is a likely culprit.