MacBook Pro M1 refresh rate of 30 Hz on a 4k monitor?

This is not a question, but an answer to https://discussions.apple.com/thread/252178220 (since the thread has been locked and I am unable to reply directly). That is, getting max refresh rate of 30 Hz even though everything supports 60 Hz:

• My MacBook Pro M1 supports 4k, 60 Hz
• My USB-C to HDMI adapter supports 4k, 60 Hz
• My HDMI cable supports 4k, 60 Hz
• My Screen (Samsung U28E590) supports 4k, 60 Hz

Yet still in Preferences -> Displays -> holding option key and clicking 'Scaled' only gave options of 30, 25 and 24 Hz.

The solution:

Use HDMI 2 instead of HMDI 1 as source on the screen.