The Mini 3 Pro appears to be lossless according to this thread:

https://forum.dji.com/thread-295842-1-1.html

When I use the 2x zoom in video on my Mini 4 Pro with latest firmware (as of 1/12/2024) the resulting video is very clearly lacking in 4K detail and appears to just be a crop of the 1x zoom.

Can anyone else confirm?

Hi, Victor. We appreciate your feedback. Let me confirm this to the related team. I will get back to you with an update. Thank you for your patience.

It's just a digital zoom, the lens is fixed and cannot zoom opitically.

Also, don't forget that shooting in 16:9 is also a "lossy" crop, meaning that you're not getting full 4k.  4:3 at 1X zoom is the only full resolution.

Hi, Thank you for patiently waiting. The Mini 4 Pro supports digital zoom, so it is normal if the quality is lower after zooming. Have a great day.

I can confirm that zoom on Mini 4 Pro is not lossless while recording video nor while taking photos. Quality degradation is very noticeable when using zoom. Unfortunately DJI does not uses the way Apple uses for digital zoom (I mean 2X sensor cropping instead of just cropping and enlarging a portion of the captured image and then using interpolation). Hopefully future DJI drones will be able to follow the way Apple does it.

Vencanator Posted at 3-24 08:22
I can confirm that zoom on Mini 4 Pro is not lossless while recording video nor while taking photos. Quality degradation is very noticeable when using zoom. Unfortunately DJI does not uses the way Apple uses for digital zoom (I mean 2X sensor cropping instead of just cropping and enlarging a portion of the captured image and then using interpolation). Hopefully future DJI drones will be able to follow the way Apple does it.

Hi there. We appreciate your feedback. Rest assured that we will coordinate this suggestion of yours to our relevant team for future consideration. Please note that the DJI Mini 4 Pro supports up to 4x digital zoom (Video 4k: 1-3x FHD: 1-4x). When zooming in or out, the larger the zoom ratio, the slower the aircraft will rotate to achieve a smooth view. Should you have other inquiries, feel free to contact us.