Kia ora Jane,
Yes, I noticed this too, our were only going back 2 years.
I think the 4 year range changed.
Check what you have in
Quick-access menu > Plugins > Logging > Manage log stores
Our "keep logs for" was set to 1000 days which explains the 2 years.
The next option is never delete logs and I'm not quite that gung ho with our site.
We've been toying with the idea of downloading the logs. Historical reporting past 2 years would need to take place in Excel but at least we would have the data.
Ngā mihi,
Larry