The compilation of conf-freeglut.1 failed at "pkg-config --exists glut".

[sanette]

[ERROR] The compilation of conf-freeglut.1 failed at "pkg-config --exists glut".
⬇ retrieved lablgl.1.07  (https://opam.ocaml.org/cache)

#=== ERROR while compiling conf-freeglut.1 ====================================#
# context     2.1.2 | linux/x86_64 | ocaml-base-compiler.5.0.0 | https://opam.ocaml.org#bbba52e4
# path        ~/.opam/5.0.0/.opam-switch/build/conf-freeglut.1
# command     ~/.opam/opam-init/hooks/sandbox.sh build pkg-config --exists glut
# exit-code   1
# env-file    ~/.opam/log/conf-freeglut-80671-fadd76.env
# output-file ~/.opam/log/conf-freeglut-80671-fadd76.out

This prevents the install of lablgl

it might be related to conan-io/conan-center-index#17131
although something must have changed recently since last year I was able to install lablgl