SQL Server 2019

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CREATE TABLE #ServerAudit (
    ServerName varchar(100) NOT NULL,
    SQLVersion varchar(50) NOT NULL,
    SQLPatchLevel varchar(20) NOT NULL,
    OS varchar(50) NOT NULL,
    OSBuild varchar(20) NOT NULL,
    Written date NOT NULL,
    BuildDate datetime NOT NULL,
    Active BIT  NOT NULL
    );
TRUNCATE TABLE #ServerAudit;
INSERT INTO #ServerAudit VALUES
    ('SrvA',' MSSQL 2017',' SP1','Windows 10 Pro','19042.1237','2021-09-26','2021-09-26 01:11', '0'),
    ('SrvA',' MSSQL 2017',' SP4','Windows 10 Pro','19042.1237','2021-10-04','2021-10-04 02:22','1'),
    ('SrvB',' MSSQL 2017',' SP1','Windows 10 Pro','19042.1237','2021-09-27','2021-09-27 03:33','0'),
    ('SrvB',' MSSQL 2017',' SP4','Windows 10 Pro','19111.1234','2021-10-05','2021-10-05 04:44','1'),
    ('SrvC',' MSSQL 2017',' SP4','Windows 10 Pro','19111.1234','2021-10-05','2021-10-05 05:55','1'),
    ('SrvD',' MSSQL 2017',' SP4','Windows 10 Pro','19111.1234','2021-10-05','2021-10-06 06:06','0')

SELECT ca2.*
FROM #ServerAudit SA1
OUTER APPLY (
    SELECT
        SA1.ServerName,  SA1.SQLVersion,  SA1.SQLPatchLevel,  SA1.OS,  SA1.OSBuild,  SA1.Written,  SA1.Active, SA1.BuildDate,
        SA2.SQLVersion AS SQLVersion2, SA2.SQLPatchLevel AS SQLPatchLevel2, SA2.OS AS OS2,
        SA2.OSBuild AS OSBuild2, SA2.Written AS Written2, SA2.Active AS Active2, SA2.BuildDate AS BuildDate2
    FROM (
        SELECT TOP (1) *
        FROM (
            SELECT ServerName, SQLVersion, SQLPatchLevel, OS, OSBuild, Written, BuildDate, Active
            FROM #ServerAudit SA2
            WHERE SA2.ServerName = SA1.ServerName AND SA2.Written < SA1.Written
            UNION ALL
            SELECT TOP (1) NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
        ) AS SA3
        ORDER BY Written DESC  
    ) AS SA2
) AS ca1
CROSS APPLY (
    SELECT CASE WHEN ca1.SQLVersion2 IS NOT NULL THEN NULL
        ELSE 'The ' + ca1.ServerName + ' new server was created on ' + CONVERT(varchar(30), ca1.BuildDate, 120) END AS Message
    UNION ALL
    SELECT 'The SQLVersion for ' + ca1.ServerName + ' has changed from ' + ca1.SQLVersion2 + ' to ' + ca1.SQLVersion + '.' AS Message
    WHERE ca1.SQLVersion <> ca1.SQLVersion2
    UNION ALL
    SELECT 'The SQLPatchLevel for ' + ca1.ServerName + ' has changed from ' + ca1.SQLPatchLevel2 + ' to ' + ca1.SQLPatchLevel + '.' AS Message
    WHERE ca1.SQLPatchLevel <> ca1.SQLPatchLevel2
    UNION ALL
    SELECT 'The OS for ' + ca1.ServerName + ' has changed from ' + ca1.OS2 + ' to ' + ca1.OS + '.' AS Message
    WHERE ca1.OS <> ca1.OS2
    UNION ALL
    SELECT 'The OSBuild for ' + ca1.ServerName + ' has changed from ' + ca1.OSBuild2 + ' to ' + ca1.OSBuild + '.' AS Message
    WHERE ca1.OSBuild <> ca1.OSBuild2
    UNION ALL
    SELECT 'The BuildDate for ' + ca1.ServerName + ' has changed from ' + CONVERT(varchar(30), ca1.BuildDate2, 120) + ' to ' +
        CONVERT(varchar(30), ca1.BuildDate, 120) + '.' AS Message --<<-- use format code 1?1 if you want the ms in the times
    WHERE ca1.OSBuild <> ca1.OSBuild2
    UNION ALL
    SELECT 'The ' + ServerName + ' old server was deleted on ' + CONVERT(varchar(30), MAX(BuildDate), 120)
    FROM #ServerAudit
    GROUP BY ServerName
    HAVING MAX(CAST(Active AS TINYINT)) = 0
) AS ca2
WHERE SA1.Active = 1
AND ca2.Message <> ''

Message
The SQLPatchLevel for SrvA has changed from SP1 to SP4.
The SrvD old server was deleted on 2021-10-06 06:06:00
The SQLPatchLevel for SrvB has changed from SP1 to SP4.
The OSBuild for SrvB has changed from 19042.1237 to 19111.1234.
The BuildDate for SrvB has changed from 2021-09-27 03:33:00 to 2021-10-05 04:44:00.
The SrvD old server was deleted on 2021-10-06 06:06:00
The SrvC new server was created on 2021-10-05 05:55:00
The SrvD old server was deleted on 2021-10-06 06:06:00