Haha. I too saw something similar. When I took up with Medium support, instead of receiving the specific reason I got the FAQ about medium partner program.

As you mentioned I am continuing to write, read and clap. I am a FOM also. Immediately after becoming FOM my earnings improved but after a month declined.

Coming back to your specific case

My guess is

The story that earned 1.21 must have received claps/response from FOM ( those get paid higher)