Changing Machine Acceleration

Hi, so I’ve been trying to diagnose why my Ortur Lasermaster 2 is causing these lines to appear horizontally and recently I found if I turn the speed down, the lines mostly disappear. For example, I used to engrave painted tiles at 6000 mm/min 50% without banding issues. Now, everything at that speed causes banding. I turned it down to 3000mm/30% which yielded decent quality engravings with minimal visible banding. Subsequent experiments between 3000 mm/min and at 6000 mm/ min show that anything above 3000mm causes banding for 4" tiles, but minimal banding for 10" canvases that travel the entire length of 254 mm with each pass at 6000mm/min.

That leads me to think that something is wrong with the stepper motors at higher speeds, such that they aren’t capable of accurate motion. For example, if I set the layer speed at 6000, I assume it tells the machine to move the Y and X axis motors at 6000mm/min even if the Y axis only moves a very short distance, instead of the Y axis moving at the minimum speed it needs to move. Am I wrong to assume that?

If I turn down the acceleration(1000 from 1800) and max travel speed for Y axis (to 5000mm/m from 9000mm/m) on the Machine Settings, and click write, does that throttle the machine motions along the Y axis?