So, after a few months I'm back to the issue. I've checked the Viltrox firmware upgrades and the docs for 1.0.4 say:
- Fixed known issues.
- Fixed the issues of uneven exposure when taking pictures with large aperture at high speed shutter.
Downloaded it, but... so far I was unable to apply it. The lens has an USB-C connector and is supposed to appear as an external volume where you drag and drop the .DAT file containing the upgrade. Nice approach... if it worked. Oh my.
Well, as I suspected, it was a cable problem. The strange thing is that it didn't work with the most recent Cable Matters cables I own, which are known to perfectly work with a number of devices, but worked with an old cable that has problems with SSD devices and that I have demoted to a power cable.
In any case... firmware upgraded, and the uneven exposure problem seems to have been really fixed.
