CGminer was originally a fully open-source software available under a General Public License (GPL) which requires anybody who modifies the code to publish their sources publicly. However, hardware manufacturers have ignored the GPL and typically do not publish their CGminer forks in a timely manner if at all. Many other firmwares also rely on CGminer but do not publish their sources.
We feature-matched CGminer in our own mining software, BOSminer, which we wrote from scratch in Rust language. This means that Braiins OS is not in violation of any GPL because it is based on BOSminer rather than CGminer.