The Fujifilm GF 30mm f/3.5 is exeamplary in its low distortion, having only a very low level of barrel distortion affecting the corners. Very few lenses of this field of view can do so well.
Kudos for this aspect of optical design!
Fujifilm GFX100S + Fujifilm GF 30mm f/3.5: Optical Distortion
Includes images with both corrected and uncorrected distortion.
f8 @ 1/80 sec, ISO 100; 2021-04-30 08:14:56[low-res image for bot]
Fujifilm GFX100S + Fujifilm GF 30mm f/3.5 R WR @ 24.6mm equiv (30mm)
RAW: vignetting corrected, push 0.65 stops, +69 Shadows, -83 Highlights, +31 Whites, +39 Dehaze, +15 Clarity