Which one is trustworthy? Bed visualizer tells me to raise, Prusa tells me to lower. I've put the G28 result intp pcby's github. This gives me the same outcome as Prusa. Do I need to change some settings in the bed visualizer?
Hard to say without seeing your settings and the response from your printer when you request the mesh report. In some cases you may need to flip the x or y in BLV to account for the way the report is provided from firmware. BLV also has options for reversing screw turn direction in the adjustment table, etc.