I guess it was sort of inevitable. I had a feeling this would happen for s2 because

1. Ranked play rewards arent enticing enough/incentivise players to not play for certain rewards
2. No series pass for s2 meaning no artificial fomo
3. Most people are finished with garo

And so what you see now is the "natural" playercount, which is a small number of incredibly dedicated players, much like the feast. I would expect the playercount to skyrocket in s3 when the new series pass comes out, and then die again for s4 etc.