That is the variation of the Unable to play h264 video in mpv on latest Tumbleweed snapshot. gstreamer-plugins-bad was rebuilt against noopenh:
Thu Jun 26 13:02:47 UTC 2025 - Bjørn Lie
- Build with noopenh264, move plugin to main package.
which means until the libopenh264-8 becomes available this plugin will not work with H.264.