Deband grain is far too strong

### mpv Information ```bash mpv v0.41.0-918-g1d1568614 Copyright © 2000-2026 mpv/MPlayer/mplayer2 projects built on Aug 2 2026 12:32:00 libplacebo version: v7.371.0 (v7.360.0-109-g4d82c68-dirty) FFmpeg version: N-125907-ga7e72069f FFmpeg library versions: libavcodec 63.7.100 libavdevice 63.2.100 libavfilter 12.3.101 libavformat 63.5.101 libavutil 61.5.100 libswresample 7.2.100 libswscale 10.2.100 ``` ### Other Information ```text - Windows version: 11 - GPU model, driver and version: RTX 4080, Game Ready 610.88 - Source of mpv: https://github.com/zhongfly/mpv-winbuild/releases - Latest known working version: mpv-x86_64-20260610-git-304426c - Issue started after the following happened: After updating mpv to latest, but it happens as far back as mpv-x86_64-20260704-git-33111f3212 (probably earlier, this is the oldest zhongfly offers) It doesn't occur with vo=gpu or gpu-api=opengl It doesn't show up in mpv screenshots, so I also took some with ShareX https://slow.pics/c/VNywxdPd ``` ### Reproduction Steps Enable deband ### Expected Behavior Debands the video will a small amount of grain ### Actual Behavior Debands the video will a huge amount of grain ### Log File [output.txt](https://github.com/user-attachments/files/30647436/output.txt) ### Sample Files _No response_ ### I carefully read all instruction and confirm that I did the following: - [x] I tested and confirmed that the issue exists with the [latest release version](https://github.com/mpv-player/mpv/releases/latest) or newer. - [x] I provided all required information including system and mpv version. - [x] I produced the log file with the exact same set of files, parameters, and conditions used in "Reproduction Steps", with the addition of `--log-file=output.txt`. - [x] I produced the log file while the behaviors described in "Actual Behavior" were actively observed. - [x] I attached the full, untruncated log file. - [x] I attached the backtrace in the case of a crash.