This is using Davinci Resolve, hope it helps
This is an excellent video and will help you be able to play and scrub in the video editor.
Then when you're done editing, you can render a file that is the appropriate resolution / quality for wherever you're going to publish it. You don't want to publish the full, raw 4K file to most social media platforms for others to view (if so, a lot of them would likely have the same judder problems you are having). Often, rendering a standard HD (1k or 2k) is fine.
The above Resolve video will not help if you just want to play the raw, 4K file right out of the aircraft. As others have already pointed out, that requires the strongest / fastest computer and components (hard drives, video cards, CPU, memory, etc.).
Getting gosh-wow results straight out of the bird is also something you might have had too great of expectations for. Really great video (as mentioned) requires post-processing. HOWEVER, you have 3 different modes you can film at and also as mentioned, D-log is the one you want to avoid if you don't want to do post processing. Try normal and HLG. See if you like it better. Do a bit of testing.
Previous DJI crafts had a "Vivid" video recording mode, which isn't on the
M2P. They may have assumed that most people with this level of recording capability would be dipping into the greater world of post-processing.
You should not get noise out of the box, at least on a bright day. As mentioned, make sure that your ISO did not get turned up to too-high values (bring it down to 100 if so).
This is the first AC of its class to have adjustable aperture. That's nice, but we've learned not to close it down further than f5.6.
For photos only (not video): If you did have a higher aperture (f8 or higher) and you have Auto-ISO on, then that would have raised the ISO and created noise.
Lastly, if the different formats, ISO, and concepts such as aperture f-stop settings are over your head, then you may want to consider doing some wood-shedding to increase your knowledge and skills to get the pro-like results you see coming from other people.
Chris