WIP…

:li:/t is a modern Microsoft 365 “link indirection” prefix used for List Item–based sharing links, where the link does not directly expose a file or site path, but instead points to an internal resource ID that SharePoint resolves at runtime.

with :li:/t links, the “managed path” (/teams/ vs /sites/) can be completely absent from the URL, even when the underlying site is clearly under /teams/....

Why Shared Links Don’t Show /sites or /teams — and How to Get the Real Site URL?
Covers why modern Microsoft 365 sharing links omit managed paths and how to use Microsoft Graph to identify the actual SharePoint site associated with a shared item.

$sharingUrl = "https://contoso.sharepoint.com/:u:/s/tst/subsite01/IQDT1WnS2vtERpmwXi1aOxruAViMmZ7-C5miAFamf6sQMnE?e=gtEfMD";
# string base64Value = System.Convert.ToBase64String(System.Text.Encoding.UTF8.GetBytes(sharingUrl));
$base64Value = [Convert]::ToBase64String([Text.Encoding]::UTF8.GetBytes($sharingUrl))
$base64Value
# string encodedUrl = "u!" + base64Value.TrimEnd('=').Replace('/','_').Replace('+','-');
$encodedUrl = "u!" + $base64Value.TrimEnd('=').Replace('/','_').Replace('+','-')
$encodedUrl

$apiUrl = "https://graph.microsoft.com/v1.0/shares/{shareId}/site"
$result = Invoke-RestMethod -Uri $apiUrl.Replace("{shareId}", $encodedUrl) -Headers $headers
$result | fl