I do have a 4k monitor but the footage I'm getting from my P3A is only 2k so I didn't played it on that screen. I've put my 2k video footage , and also 1080p on Premiere Pro and also some 4k video I got on vimeo (I can download the original files from the uploader) just to see how sharp is the video when saw at 100% scale and it isn't very sharp or with much detail but when viewed at 50% ou on a brower window everything seems to be pretty good , my footage not so much even on a small window. That's when I started thinking my camera is softer than supposed, then I've shown the DNG to several persons and it seems that everyone notices that the left side is sharper than the center so I guess that small difference is enough to be seen at video footage also making it a softer. I could always add unsharp masking in post but I guess I would sleep better at night knowing that my camera is pretty on spot when it comes to sharpness / focus since I want to use my P3 to video production. On the other side I don't know if I'm just getting paranoid and there isn't much difference in sharpness on my videos compared to what I see on vimeo / youtube.
Aaaaahhhhh.... That is "part" of your problem. You're blowing up a 2.7 K vid onto a 4 K monitor. Crisp details will be no more.
I do have a Phantom Advanced which has the same sensor and lens as the Phantom Professional. I also have a Phantom Standard. There is a big difference between the two. The Phantom Standard lens is what I would call a "true lens". It does not distort objects on the right and left sides like the Phantom Standard & Professional (you notice it big time if you hover and spin 360 degrees... objects on the sides stretch & compress).
I also find that the Phantom Standard camera is unaffected by temperature (hot/cold) or climate (humid, dry) and produces an extremely crisp photo and video. In my experience the Phantom Advanced/Professional camera is affected by temperature and climate.
The Phantom Advanced/Professional camera lens design is made to accommodate numerous picture resolutions/size. Because of this it seems DJI had to make a lens that tends to squish the image in the centre and stretch the sides. Firmware in the camera quickly adjusts the photo to a non fish-eye look at select resolutions.
When my Phantom Advanced camera is cold (temperatures below freezing or slightly above), the centre of the picture becomes much softer/less sharp. This tells me that the metal internals inside the camera are contracting under the cold and moving the sensor/lens slightly out of alignment.
I had a look at your photos. The photos taken of the apartment block look fine. Some of the others, not so fine. It's almost as if the aperture is letting in too much light. Your video also looks fine. You could reduce the softness by going into the camera settings and select STYLE and then LANDSCAPE (think that's what it's called). It increases your sharpness & contrast by a factor of 1... it's worth a try if you have not already tried it.
You could also try using an ND8 Filter (some are bad, some are average and some are great). The ND8 I use is my goto filter for filming during sunrise/sunset/bright sunny day. It gives a super cool lens flare when moving away from the sun and also provides that golden colour & blue sky in the early morning or late evening. Items appear more in focus on a sunny day with this filter. Also it does not screw on a lens, it slides on which makes it a breeze for putting it on/taking it off. It may help your camera. The one I use is (link to Canadian site):
niceEshop(TM) ND8 Filter Lens for Dji Phantom 3 Professiona Advanced Camera (Black+ND8): Amazon.ca: Camera & Photo
You may not wish to try the following, it's your call.... I did read that since temperature affects the camera, some users have placed their Phantom (without battery) in the Freezer for 15 or 30 mins or so in hopes that the cold would contract internal camera parts. Then let Phantom sit at room temperature for an hour to see if things returned to a proper alignment. I guess this would be no different than when I go out flying at massively cold arctic temps here in Canada during February (the camera is negatively affected in regards to focus.. center becomes very soft focus), but everything goes back to normal once back at room temperature, so items are moving inside.
Good luck!