Amazon Fire TV Stick 4K picture dropouts?

I've had an Amazon Fire TV Stick 4K for a few weeks.
Ever since I've had that, I've constantly had picture dropouts that run across the screen like white flashes and a loud electrical noise (high-pitched crackling) when I'm on the Amazon homepage.
This does not happen with my Sky Q Receiver, PlayStation or other applications (e.g. Netflix)!

I even got a replacement device from Amazon, but there, too, I have the same problems in green.

I've only had the television for about half a year.

it won't be because of that.
Using other HDMI connections did not help either

Does anyone have the problem and was able to fix it?
I'm so slowly desperate.

That looks a lot like a defect on the television. Does it flicker in "normal operation" also or only when using the stick?

If only with the stick, there's probably something wrong with the HDMI port

Test on another TV…

As I said, I use a PlayStation via the port, now and then a switch and the Fire Tv Stick.
I have no problem on any port until the stick is in.
Then it only starts to flicker.