And we have checked our server log, robot file and also response time. Didn't find anything wrong. Also, didn't see any google algorithm update on crawling.
This drop trend didn't affect traffic for now. So the site is not penalized.
yes, stats are from gsc and also our company's own log report. here is the screenshot in gsc: https://ibb.co/NNzZjvw.
Our daily crawel request drop from 6m to 60k on 9th, Oct, and it didn't recover yet.