Any way to preserve video effects in output clip? (Speed, Pitch, ect.)

[Bonboon229]

Windows 10 x64 (Unsure of build version)

mpv v0.38.0-727-g938938a9 Copyright © 2000-2024 mpv/MPlayer/mplayer2 projects
built on Aug 27 2024 00:14:48
libplacebo version: v7.349.0 (v7.349.0-5-g82bf46a-dirty)
FFmpeg version: N-116778-g7e4784e40
FFmpeg library versions:
libavcodec 61.11.100
libavdevice 61.2.100
libavfilter 10.2.102
libavformat 61.5.101
libavutil 59.34.100
libswresample 5.2.100
libswscale 8.2.100

I tried modifying the script to ensure speed effects are preserved, to no luck...
Any recommendations I could try to ensure the effects are preserved in output?