Bad resolution, recording to disk

Hello,

 last two weeks, the quality of the recording to disk in Wirecast has become very bad. Which is strange, because the exact same settings never gave us any problems before. 

Technical: Macbook Pro (2021) - screen resolution 1920*1080, 50fps, bitrate 6000

We tried lowering the framerate, lowering the bitrate, but that didn't solve the problem. Edges keep looking blocky/pixeled.

Any help is greatly appreciated.