Meaningless warning when using vf-remove with a label in a profile

Important Information

Provide following Information:

• mpv version

mpv 0.33.1 Copyright © 2000-2020 mpv/MPlayer/mplayer2 projects
 built on UNKNOWN
FFmpeg library versions:
   libavutil       56.70.100
   libavcodec      58.134.100
   libavformat     58.76.100
   libswscale      5.9.100
   libavfilter     7.110.100
   libswresample   3.9.100
FFmpeg version: 4.4

• Platform and Version
  NixOS Linux
• Source of the mpv binary
  Nixpkgs unstable

Reproduction steps

In mpv.conf put:

vf=@f:format=yuv420p
[test]
vf-remove=@f

Expected behavior

mpv interprets the config in the obvious manner.

Actual behavior

mpv interprets the config in the obvious manner, but also prints a warning:

Option vf-toggle: Label f not found

This warning seems to have no effect, as setting the profile in the command-line (--profile=test) and while mpv is running (apply-profile test or vf toggle @f) works perfectly.

Log file

mpv.txt

Sample files

null://

Reproduce the warning using the mpv.conf profile with vf=@f:format=yuv420p and vf-remove=@f, then compare it with --profile=test, apply-profile test, and vf toggle @f. Trace the handling of the vf-remove label and the resulting "Option vf-toggle: Label f not found" message; done means the configuration still works without this meaningless warning.