I just wanted to be one of the first to write Linux® with the appropriate trademark sign.

Apparently, Linux is now trademarked, and they want companies to pay to use the trademark, which I assume is targeted towards the various Linux distributions. An organization called the Linux Mark Institute was formed “to protect the public and Linux® users of the world from unauthorized and confusing use of the Linux mark and to issue proper licenses to authorized users of the Linux mark.”

Linux® is the registered trademark of Linus
Torvalds in the U.S. and other countries.

Link: Linux Mark Institute