SQL Server 2016

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CREATE TABLE #Example
(
	UniqueID INT IDENTITY(1,1)
  , GroupID INT
  , GroupDate DATETIME
  , UniqueDate DATETIME
)

CREATE CLUSTERED INDEX [CX_1] ON [#Example]
(
	[UniqueID] ASC
)

SET NOCOUNT ON

--Populate some test data
DECLARE @i INT = 0, @j INT = 5, @UniqueDate DATETIME, @GroupDate DATETIME

WHILE @i < 10000
BEGIN

IF((@i + @j)%173 = 0)
	BEGIN
		SET @UniqueDate = GETDATE()+@i+5
	END
	ELSE
	BEGIN
		SET @UniqueDate = GETDATE()+@i
	END
	
	SET @GroupDate = GETDATE()+(@j-1)

INSERT INTO #Example (GroupID, GroupDate, UniqueDate)
	VALUES (@j, @GroupDate, @UniqueDate)

SET @i = @i + 1
	
	IF (@i % 5 = 0)
	BEGIN
		SET @j = @j+5
	END
END
SET NOCOUNT OFF

CREATE NONCLUSTERED INDEX [IX_2_4_3] ON [#Example]
(
	[GroupID] ASC,
	[UniqueDate] ASC,
	[GroupDate] ASC
)
INCLUDE ([UniqueID])

-- Identify any UniqueDates that are greater than the GroupDate within their GroupID
SELECT UniqueID
	 , GroupID
	 , GroupDate
	 , UniqueDate
FROM (
	SELECT UniqueID
		 , GroupID
		 , GroupDate
		 , UniqueDate
		 , MAX(UniqueDate) OVER (PARTITION BY GroupID) AS maxUniqueDate
	FROM #Example
	) calc_maxUD
WHERE maxUniqueDate > GroupDate
	AND maxUniqueDate = UniqueDate

DROP TABLE #Example

UniqueID	GroupID	GroupDate	UniqueDate
172	175	05/10/2017 19:28:46	07/10/2017 19:28:46
260	260	29/12/2017 19:28:46	03/01/2018 19:28:46
431	435	22/06/2018 19:28:46	23/06/2018 19:28:46
519	520	15/09/2018 19:28:46	19/09/2018 19:28:46
778	780	02/06/2019 19:28:46	05/06/2019 19:28:46
1037	1040	17/02/2020 19:28:46	19/02/2020 19:28:46
1125	1125	12/05/2020 19:28:46	17/05/2020 19:28:46
1296	1300	03/11/2020 19:28:46	04/11/2020 19:28:46
1384	1385	27/01/2021 19:28:46	31/01/2021 19:28:46
1643	1645	14/10/2021 19:28:46	17/10/2021 19:28:46
1902	1905	01/07/2022 19:28:46	03/07/2022 19:28:46
1990	1990	24/09/2022 19:28:46	29/09/2022 19:28:46
2161	2165	18/03/2023 19:28:46	19/03/2023 19:28:46
2249	2250	11/06/2023 19:28:46	15/06/2023 19:28:46
2508	2510	26/02/2024 19:28:46	29/02/2024 19:28:46
2767	2770	12/11/2024 19:28:46	14/11/2024 19:28:46
2855	2855	05/02/2025 19:28:46	10/02/2025 19:28:46
3026	3030	30/07/2025 19:28:46	31/07/2025 19:28:46
3114	3115	23/10/2025 19:28:46	27/10/2025 19:28:46
3373	3375	10/07/2026 19:28:46	13/07/2026 19:28:46
3632	3635	27/03/2027 19:28:46	29/03/2027 19:28:46
3720	3720	20/06/2027 19:28:46	25/06/2027 19:28:46
3891	3895	12/12/2027 19:28:46	13/12/2027 19:28:46
3979	3980	06/03/2028 19:28:46	10/03/2028 19:28:46
4238	4240	21/11/2028 19:28:46	24/11/2028 19:28:46
4497	4500	08/08/2029 19:28:46	10/08/2029 19:28:46
4585	4585	01/11/2029 19:28:46	06/11/2029 19:28:46
4756	4760	25/04/2030 19:28:46	26/04/2030 19:28:46
4844	4845	19/07/2030 19:28:46	23/07/2030 19:28:46
5103	5105	05/04/2031 19:28:46	08/04/2031 19:28:46
5362	5365	21/12/2031 19:28:46	23/12/2031 19:28:46
5450	5450	15/03/2032 19:28:46	20/03/2032 19:28:46
5621	5625	06/09/2032 19:28:46	07/09/2032 19:28:46
5709	5710	30/11/2032 19:28:46	04/12/2032 19:28:46
5968	5970	17/08/2033 19:28:46	20/08/2033 19:28:46
6227	6230	04/05/2034 19:28:46	06/05/2034 19:28:46
6315	6315	28/07/2034 19:28:46	02/08/2034 19:28:46
6486	6490	19/01/2035 19:28:46	20/01/2035 19:28:46
6574	6575	14/04/2035 19:28:46	18/04/2035 19:28:46
6833	6835	30/12/2035 19:28:46	02/01/2036 19:28:46
7092	7095	15/09/2036 19:28:46	17/09/2036 19:28:46
7180	7180	09/12/2036 19:28:46	14/12/2036 19:28:46
7351	7355	02/06/2037 19:28:46	03/06/2037 19:28:46
7439	7440	26/08/2037 19:28:46	30/08/2037 19:28:46
7698	7700	13/05/2038 19:28:46	16/05/2038 19:28:46
7957	7960	28/01/2039 19:28:47	30/01/2039 19:28:47
8045	8045	23/04/2039 19:28:47	28/04/2039 19:28:47
8216	8220	15/10/2039 19:28:47	16/10/2039 19:28:47
8304	8305	08/01/2040 19:28:47	12/01/2040 19:28:47
8563	8565	24/09/2040 19:28:47	27/09/2040 19:28:47
8822	8825	11/06/2041 19:28:47	13/06/2041 19:28:47
8910	8910	04/09/2041 19:28:47	09/09/2041 19:28:47
9081	9085	26/02/2042 19:28:47	27/02/2042 19:28:47
9169	9170	22/05/2042 19:28:47	26/05/2042 19:28:47
9428	9430	06/02/2043 19:28:47	09/02/2043 19:28:47
9687	9690	24/10/2043 19:28:47	26/10/2043 19:28:47
9775	9775	17/01/2044 19:28:47	22/01/2044 19:28:47
9946	9950	10/07/2044 19:28:47	11/07/2044 19:28:47