Originally, I found this problem using Siril.

I reproduced it using dcraw_emu.exe directly using LibRaw-0.21.2-Win64 (downloaded today, Mar 28, 2024).
To view the source and destination images, I use FastImage Viewer, and Adobe Photoshop.

Scenario:
1. Take sequence of CR3 raw (not cRAW) images of while flat backround using Canon R6 mark II just holdiong the button. All the camera settings and image pramaters are exactly the same.
Say, we took KM1A2297.CR3 and KM1A2298.CR3 . Both 6000 x 4000.
2. Do convert them to TIFF using
dcraw_emu.exe -T KM1A2297.CR3
dcraw_emu.exe -T KM1A2298.CR3
and get KM1A2297.CR3.tiff and KM1A2298.CR3.tiff
3. See that :
* KM1A2297.CR3.tiff is of 5999 x 3999 and looks OK.
* KM1A2297.CR3.tiff is of 6188 x 4120 and looks weird (it is not white at all, and the are regions of different colors instead of being just white)

Expected result:
KM1A2297.CR3.tiff must be of 5999 x 3999 and be just white but its not.
Here are the discribed files: https://drive.google.com/drive/folders/1u1NWWyu_d_vvufA5Qw-qxu3YZlqSPsRD...

Please fix this in the library to it converts CR3 files without damaging the image. Thanks!

PS Canon R6m2 is not on list of the supported cameras. It looks like it writes something dirrefent than Canon R6. Please make Canon R6m2 supported by your great lib!
PPS Please let me know if you need more examples of CR3 files of Canon R6m2. I will send as many as you need and may take part in beta testing.