I recently had a new camera and gimbal installed on my Mavic because I accidentally damaged the old gimbal. The new camera worked good for the first few flights, but now I'm having issues.
1) Manual focus - Works fine for focusing close, but when I scroll to infinity everything is blurry, even objects 150 feet away. Found this out trying to focus on fireworks, couldn't get them in focus, so next day I did some experimenting. I found the half-way setting is the sharpest result for infinity focus. Is this the case with all Mavic cameras, or do I have a dud?
2) While flying and viewing what the Mavic sees, I now always get red pixels and lines on the edges of most objects on my screen (iPhone 7+). This doesn't appear on the recorded images on the SD card, but is annoying while trying to see what I'm shooting. Really doesn't bother me much, 'cause it doesn't show on the actual pictures, but it points to the notion that something is wrong.
3) I really think that my videos and pictures were sharper before, now they are more like 6 megapixel photos, but can't say for sure, I'd have to preform some more experiments.

If anyone has heard of these Mavic camera problems before, please help.

The red pixels are a feature called Focus Peaking, the pixels show the areas in focus. The Mavic FAQ documents that in manual focus you can focus past infinity, so this is a known behavior. You can disable Focus Peaking if it bothers you, but I find it a helpful reality check. Hope this helps.

Agree with Ex Machina. The focus range of the Mavic is 0.5m to infinite. Sliding straight to infinite focus does not guarantee sharp focus. I would recommend you to adjust the focus according to the specific scene and disable the Focus Peaking.

Thank you Ex Machina, and Susan. I now feel better with piece of mind.