The alerts show the last 15 days I believe.
If you have the option for advanced hunting under security.microsoft.com, you can run this, changing the date and the
>ago(1d)
DeviceInfo //| summarize by DeviceName| where Timestamp > startofday(datetime(2021-11-15 00:00:01))| join (AlertEvidence | where Timestamp > ago(1d)) on DeviceName| summarize count() by DeviceName