Apologies for the size of these, I promise that next time I do this they will be smaller. Trying to follow more of Fred's lead in posting comparisons (thanks Fred!.) These were taken with all in camera corrections off, on a tripod, manually focused. They were processed in Lightroom Classic, all corrections off (although it said it was using a built in profile for the Tamron.) I used the same sharpening for both lenses (matching Fred's.)
All were taken on my a7R III, which is probably limiting some of the ability to cross compare.....but it's all I have.
These are center crops.
Left - Tamron 35mm f/2.8 Di III OSD 1:2 / Right - Voigtlander APO-Lanthar 35mm f/2 Aspherical