Not sure what MSI are doing, but if you under-volt you can often get higher clock with less power consumed (Or put another way, your XXX watts goes further at lower voltage - assuming your chip can run under-volted at that speed).
I managed to run Vega 64 down around 1.075v which cut a huge amount of heat and power consumption - which meant the 100% power budget goes further - clocks can stay higher for longer due to less heat and “more power budget” available - as lower volts means lower watts required for same clock.
That does not surprise me. Vega56 is power crippled (out of the box), less volts = same watts go further…
If all you do is lower the power limit you will lower the clocks the board can reach. Voltages are what you want to play with to try and make it use less power for a given clock.
The power budget is just like a tap on a fire hose - thats how much the card can play with.
Voltage is how much you use to drive it.
By setting the power limit to +50% for example and the voltages to say 1.1v you will likely get higher sustained clocks and less heat than stock. The +50 power limit won’t mean that it will instantly consume 50% more. It just CAN if required (but it won’t be, due to the lower volts, most likely).