Not sure if it is intended or not, but if you run a docker container with --tty, many queries termenv does timeout.

Minimum reproducible:

// main.go
package main

import (
	"fmt"

	"github.com/muesli/termenv"
)

func main() {
	fmt.Println("BG", termenv.BackgroundColor())
}

GOOS=linux GOARCH=amd64 CGO_ENABLED=0 go build -o a .
docker run --rm --tty -v $PWD:/tmp alpine /tmp/a