sometimes copyright law is just a funny mess, the leaked Signal screenshots are public domain because they are authored by federal US government employees, but the emojis are copyrighted by Apple, though Wikimedia Commons considers them acceptable under the de minimis doctrine

https://commons.wikimedia.org/wiki/File:US_Govt_Signal_leak_screenshot_3.png

apparently UTC has a logo

https://www.bipm.org/en/time-ftp/circular-t