Very degraded quality when against non-sky background

I cant imagine this is intended behaviour but when objects are against the sky as a background the sharpness of the depthmap is amazing but as soon as the background shifts to being ground or something else it quickly becomes noticeably more blurry and in some cases looks like errors, is this intended behaviour? i used the mono model for this test, you can see especially around 10 seconds until 15 seconds in the video where the trees that have the sky as the background changes to ground and they lose all the detail:

https://github.com/user-attachments/assets/06e18b7b-f4d2-42b5-81b2-2c9ce2a6ff50

here is the source video:

https://github.com/user-attachments/assets/391b02a8-c08c-470c-bed7-c3a8773e5e9d

Link to original video:

https://www.pexels.com/video/fpv-bridge-17516933/