The optical design of the Fujifilm GF 63mm f/2.8 R WR relies on software correction, requiring corrections for distortion, vignetting and chromatic aberration. This page looks at the true optical distortion of the 63/2.8, which is moderately high.
Distortion correction in software is never desirable in quality terms, primarily because it always has some effect on micro contrast, which puts a hard limit on how crisp an image can look (image pixels have to be remapped by some fractional number of pixels).
While the Fujifilm GFX corrects the distortion for viewing purposes while shooting, the raw file is recorded without distortion correction applied, and some field of view is lost by correcting it. Worse, the GFX sets a flag in the raw file that requires corrections, which Adobe Camera Raw offers no option to ignore.
Image sizes up to full resolution.