Run "ELS logs/received" at 2 difference time-slot, then received huge difference amount of logs

More details in my case:

#1 In one hour

index 15: 1542697200000000001==>1542700800000000000
[logshare-cli] 18:05:47 HTTP status 200 | 690ms | https://api.cloudflare.com/client/v4/zones/XXX/logs/received?
[logshare-cli] 18:05:47 Retrieved 2548 logs

index 15: 1542697200000000001==>1542700800000000000
[logshare-cli] 02:09:25 HTTP status 200 | 343ms | https://api.cloudflare.com/client/v4/zones/XXX/logs/received?
[logshare-cli] 02:09:25 Retrieved 221292 logs

#2 In 24 hours

Total number of log in 1st run (20 Nov, at 17:00:00 UTC): 1522632
Total number of log in 2nd run (21 Nov, at 02:04:00 UTC): 2705880