LastContentModifiedDate using PowerShell not equal to actual date in SharePoint Admin

[Istvan Ybema]

I've created a report using PowerShell to get an overview of inactive SharePoint Sites using the LastContentModifiedDate property of the SharePoint object.

But when I compare the date to the last modified in the SharePoint Admin I'm getting a different date.
It looks like the LastContentModifiedDate is nog reflecting the correct date.

Tried this on different Tenants and SharePoint sites. Is this correct of is there a better way to get the Last-Content-Modified date using powershell?

[#2]

@Istvan Ybema 

Apparently that date gets update by some kind of timer job.
You can find the correct date with the LastItemUserModifiedDate property of the web object.

$oWeb = Get-PnPWeb -Includes LastItemUserModifiedDate
$oContentModifiedDate = $oWeb.LastItemUserModifiedDate

[#3]

What would this be like?
I mean... I looked for how to do it and in the end, via Powershell Script I used 'Get-PnPTenantSite'.
Basically it is:
...
$DaysInActive = 140
$SiteCollections = Get-PnPTenantSite
$Date = (Get-Date).AddDays(-$DaysInActive).ToString("MM/dd/yyyy")
$InActiveSites = $SiteCollections | Where {$_.LastContentModifiedDate -le $Date} | Select Title, Url, LastContentModifiedDate, Template, StorageMaximumLevel
$InActiveSites
...
And I always have the same impression. That the date is very close. How can it be done to obtain a more accurate date?