Suspicious modification of Global Administrator user properties

Original query, unchanged.

let query_frequency = 1h;
let query_period = 14d;
IdentityInfo
| where TimeGenerated > ago(query_period)
| where set_has_element(AssignedRoles, "Global Administrator")
| distinct AccountUPN, AccountObjectId
| join kind=inner (
    AuditLogs
    | where TimeGenerated > ago(query_frequency)
    | where OperationName=~ "Update user" and Result =~ "success"
    // | where isnotempty(InitiatedBy["user"])
    | mv-expand TargetResource = TargetResources
    | where TargetResource["type"] == "User"
    | extend AccountObjectId = tostring(TargetResource["id"])
    | where tostring(TargetResource["modifiedProperties"]) != "[]"
    | mv-apply modifiedProperty = TargetResource["modifiedProperties"] on (
        summarize modifiedProperties = make_bag(
            bag_pack(tostring(modifiedProperty["displayName"]),
                bag_pack("oldValue", trim(@'[\"\s]+', tostring(modifiedProperty["oldValue"])),
                    "newValue", trim(@'[\"\s]+', tostring(modifiedProperty["newValue"])))))
    )
    | where not(tostring(modifiedProperties["Included Updated Properties"]["newValue"]) in ("LastDirSyncTime", ""))
    | where not(tostring(modifiedProperties["Included Updated Properties"]["newValue"]) == "StrongAuthenticationPhoneAppDetail" and isnotempty(modifiedProperties["StrongAuthenticationPhoneAppDetail"]) and tostring(array_sort_asc(extract_all(@'\"Id\"\:\"([^\"]+)\"', tostring(modifiedProperties["StrongAuthenticationPhoneAppDetail"]["newValue"])))) == tostring(array_sort_asc(extract_all(@'\"Id\"\:\"([^\"]+)\"', tostring(modifiedProperties["StrongAuthenticationPhoneAppDetail"]["oldValue"])))))
    | extend
        Initiator = iif(isnotempty(InitiatedBy["app"]), tostring(InitiatedBy["app"]["displayName"]), tostring(InitiatedBy["user"]["userPrincipalName"])),
        InitiatorId = iif(isnotempty(InitiatedBy["app"]), tostring(InitiatedBy["app"]["servicePrincipalId"]), tostring(InitiatedBy["user"]["id"])),
        IPAddress = tostring(InitiatedBy[tostring(bag_keys(InitiatedBy)[0])]["ipAddress"])
) on AccountObjectId
| project TimeGenerated, Category, Identity, Initiator, IPAddress, OperationName, Result, AccountUPN, InitiatedBy, AdditionalDetails, TargetResources, AccountObjectId, InitiatorId, CorrelationId
| extend
    InitiatorName = tostring(split(Initiator, "@")[0]),
    InitiatorUPNSuffix = tostring(split(Initiator, "@")[1]),
    AccountName = tostring(split(AccountUPN, "@")[0]),
    AccountUPNSuffix = tostring(split(AccountUPN, "@")[1])