Inexplicable banding?!

[Stef DK]

Can anyone explain this banding on just 2 images in a series of approx. 90?
Is there anything wrong with the shutter on my A7iii?
Shot with Viltrox 85/1.8 - 1/800 - f/5.6

• ILCE-7M3
• Viltrox 85mm F1.8
• 85.0 mm
• ƒ/5.6
• 1/1000 sec
• ISO 100

• ILCE-7M3
• Viltrox 85mm F1.8
• 85.0 mm
• ƒ/5.6
• 1/800 sec
• ISO 100

 

[Stef DK]

Apparently when look at the images on my camera display, there's nothing wrong with the picture.
So maybe it's just a copying mistake on the sd-card...?