High Sierra strange video glitches

Hello together! :)
Since a short time I'm also the proud owner of a Hackintosh. (High Sierra)

It runs pretty well but I'm experiencing very strange glitches in video playback:

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https://preview.redd.it/e71a7e2smue61.png?width=1829&format=png&auto=webp&s=406759166e57b572582d70f42a42451e09dae9fc

In the finder preview and in Premiere & After Effects the playback of videos is totally glitching out. : (

If I open the same videos in Quicktime Player it's playing flawlessly.
This happens with .mp4 and also .mov files.
Is somebody familiar with this issue?
I would be extremely grateful if someone could help me with this problem!

Here are my specs:

Mainboard: Gigabyte Z370 Aorus Gaming 7

Graphics card: Radeon RX 570

Ram: 32GB Corsair Vengeance LPX black DDR4-2666 DIMM CL16 Dual Kit

CPU: Intel Core i7-8700K processor

Hard disk: Samsung SSD 970 EVO Plus 500GB

Best regards,
Chris