Block Artifacts in Lightroom Slideshow

[Andreas5D2C]

When creating a slideshow in Lightroom often some pictures are presented with block artifacts. This also applies to exported MP4-slideshows.

This happens to me in more or less everay slideshow.

It is independent from the camera I've used.

This makes the slideshow unusable for me.

MacBook Pro (16 inch, 2019); 2,3 GHz 8-Core Intel Core i9; RAM 32 GB 2667 MHz DDR4; Graphic AMD Radeon Pro 5500M 4 GB

Is there a solution?

[GoldingD]

Does it behave differently if /preferences/performance/use graphics processor/ is off?

[Andreas5D2C]

It makes no difference if off, automatically or user defined. What I've recognized during the test: The fullscreen view of an image shows the same effect as when it is displayed during a slideshow.