I have a few Leica and Voigtlander M mount lenses I use on my Sony A7. Although the wider lenses are more likely to suffer from smear and colour shifts in the corners, it is not just focal length.
Looking at some of them, one by one, the further the rear element of the lens extends beyond the M mount bayonet, the worse the problem seems to be.
CV15 - rear element protrudes a lot, approximately 7mm beyond the mount/13mm beyond flange - bad smearing and magenta colour shift
CV Ultron 28/1.9 - 3mm/9mm no/minimal smear or colour
Lux 50 - rear element within bayonet - no problems
CV Nokton 50/1.5 - rear element well within the mount bayonet - no problems
It would be interesting to hear from other people about which lenses perform well and which badly, and their matching measurements.
Julian