Dataverse - Suspicious use of Web API

Original query, unchanged.

let query_frequency = 1h;
let query_lookback = 24h;
// AppID of the multi-tenant Dynamics 365 Example Client Application
let well_known_app_id = "51f81489-12ee-4a9e-aaae-a2591f45987d";
let environment_count_threshold = 10;
SigninLogs
| where TimeGenerated >= ago(query_lookback)
// Comment out the line below to monitor activity from all Azure AD apps
| where AppId == well_known_app_id
| where ResourceIdentity == '00000007-0000-0000-c000-000000000000'
| summarize FirstSeen = min(TimeGenerated) by AppId, UserPrincipalName, IPAddress, AppDisplayName
| join kind=inner (
    DataverseActivity
    | where TimeGenerated >= ago(query_frequency)
    | where Message == "UserSignIn")
    on $left.UserPrincipalName == $right.UserId, $left.IPAddress == $right.ClientIp
| where TimeGenerated between (FirstSeen .. (FirstSeen + 2h))
| summarize InstanceCount = dcount(InstanceUrl, 4), FirstSeen = min(FirstSeen) by UserId, ClientIp, InstanceUrl, AppDisplayName, AppId
| where InstanceCount > environment_count_threshold
| extend
    CloudAppId = int(32780),
    AccountName = tostring(split(UserId, '@')[0]),
    UPNSuffix = tostring(split(UserId, '@')[1])
| project
    FirstSeen,
    UserId,
    ClientIp,
    AppDisplayName,
    AppId,
    InstanceUrl,
    CloudAppId,
    AccountName,
    UPNSuffix