Try:
DECLARE @d1 date = DATEADD(QUARTER,-1, CURRENT_TIMESTAMP)
DECLARE @d2 date = DATEADD(QUARTER,-2, CURRENT_TIMESTAMP)
SELECT FORMAT(@d1, 'yyyy') + CONCAT('Q', DATEPART(QUARTER,@d1)) AS Previous ,
FORMAT(@d2, 'yyyy') + CONCAT('Q', DATEPART(QUARTER,@d2)) AS [2 Quarters Back]