One reason could be the 1/4 of max number of votes of full power. If oyu are human, back then, you probably just spread your votes to anything with a nice headline to get curation reward. Those numbers are down by 3/4.

But I guess the main reason is the high number of short time accounts/money grabbers.

Sometimes back I had 200 followers. That was a huge party, and I gave away 40SBD. Took me half a year or longer to get that.

Then my number of followers skyrocketed, and that was not because I wrote especially much or good content.
Most of those followers are, as far as I can tell, the "I follow you, follow me back" spamers, that may or may not be bots.