van0014, the Rosc resistor isn't an "either/or" value. It's value in ohms determines what percentage of time the driver spends in mixed decay mode. The stock Tri-Gorilla board from Anycubic uses a 1% 10K resistor, like yours. Increasing that value would make the driver spend less time in mixed decay, and reducing the value to zero (a short, as you have done) forces the driver into mixed decay all the time. At all speeds.
Be aware that "running slow" according to Allegro, is on the order of 10 steps per second or so, or about 30% of the driver chips main oscillator frequency. You can modify "running slow" by changing the main oscillator capacitor value, but your fix is cleaner and easier. These drivers don't even begin to task the maximum speed of the motors, especially at 24 volts, so grounding the Rosc pin on the Allegro A4988 can only be good for us.
For what it's worth, just "bridging" R49 with some solder is just as effective as removing the resistor and bridging the remaining pads. 10Kohm in parallel with zero ohms is zero ohms. Less potential board damage, and you can just remove the solder bridge on the resistor to get back to where you started.