If there is no mechanical problem present you could avoid that problem by setting up separate filament profiles for the right extruder with higher flow rate (the lazy way).
The correct way would be to calibrate extrusion. Here is a guide how to do that for a single extruder printer: https://3dprintbeginner.com/extruder-calibration-guide/
Note: When following the calibration guide you need to select the current extruder by sending the T1 g-code command for the right extruder and T0 for the left one. The M92 g-code command has to be altered to M92 T1 E###.# for the right extruder and M92 T0 E###.# for the left one.