Seems dev dont disclose Even Fight events data as usual.
Participants: 419x(20~100)= 8k~42k
At least this amount of individual players joined this event during recent 10 days.
You can peak through this data for how many “core” players (players have interest to join the event) here
A reference:
Previous event (Jun 2022) had >20.5k participants.
Still, dont know if game count those players with minus scores/ratings.