K5 High ISO very strong banding - any other experiences?

See both pictures.

I was working with DA*300mm and hence wanted short exposure time so worked in TAv mode. As there was little amount of light, ISO went all the way up.

I have got banding on a lot of pictures but not all, mostly banding at the top of the frame - having no colour - and one time serious colour banding at the bottom of the frame.

I feel it might be connected with shooting a lot of pictures in a short while. I sometimes had to wait for being able to view the pictures on the camera's LCD screen.

Haven't seen this before with our K5.

I searched the forum but did not see anything like this.

Any suggestions / opinions would be very welcome.

A greyish banding close to the top of the frame

Strong coloured banding at the bottom

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Kind Regards / Met vriendelijke groet,
Jetze