Both YI M1 and Canon G9 X II have 20.0 MP resolution sensors but YI M1's sensor is Four Thirds (17.3 x 13 mm ) and Canon G9 X II's sensor is 1-inch (13.2 x 8.8 mm ).
Since YI M1's has a larger sensor area with the same resolution, this means that it also has a larger pixel area hence better light collecting capacity for a given aperture compared to Canon G9 X II.
Below you can see the M1 and G9 X II sensor size comparison.
As seen above, YI M1 has a 1.9x Larger sensor area than Canon G9 X II. Larger sensors give photographer more control on the depth of field and blurry background compared to smaller sensor when shot in same focal length and aperture.