I think the earnings were better back in August and September because of all the new accounts signing up.
However, many of these accounts seem to be really active and they have probably used up all of their available earnings to give out, which is one reason why the earnings per read are much lower. Instead of giving out 25 or 30 cents, they might be giving out one or two cents for reading and leaving a comment.
The combination of more content on Medium and all of the AI junk also makes it harder for legit articles to stand out from everything else.
That's my theory, but who really knows. I do know the earnings per read were much better until the past few months.