Forced Serialization on SQL Server 2019

Question

I ran Brent Ozar's BlitzCache and it identified a query that is executing with Forced Serialization. I'm assuming it is because of the Calendar functions contained with the query. I was looking for options to remedy it and learned that the Froid feature in SQL Server 2019 is supposed to prevent Forced Serialization from occurring. I have the database set to 2019 (150) compatibility. Is there a reason this query is not benefitting from Froid?

    select
      DATEADD(q, DATEDIFF(q, 0, MonthOfDate), 0) as Quarter
      ,[PartnerCD]
      ,[PartnerNM]
      ,[PartnerGRPNM]
      ,[CCOMemberID]
      ,[MemberID]
      ,[CCOType]
      ,[RateCD]
      ,[Rate]
      ,sum([MemberMonth]) as MemberQuarter
      ,[CurrentAge]
      ,[AgeAtTime] = CASE WHEN dbo.fn_CalculateAge(BirthDT, (DATEADD(q, DATEDIFF(q, 0, MonthOfDate), 0)), 'YEAR') < 0 THEN NULL ELSE dbo.fn_CalculateAge(BirthDT, (DATEADD(q, DATEDIFF(q, 0, MonthOfDate), 0)), 'YEAR') END
      ,AgeCategory = dbo.fn_CalculateAgeCatYrsOrdered(BirthDT, (DATEADD(q, DATEDIFF(q, 0, MonthOfDate), 0)))
      ,[BirthDT]
      ,[Gender]
      ,[Language]
      ,[RaceEthnicity]
      ,[ZipCD]
FROM [BIP].[QDS].[Enrollment_Monthly]  
group by DATEADD(q, DATEDIFF(q, 0, MonthOfDate), 0)
      ,[PartnerCD]
      ,[PartnerNM]
      ,[PartnerGRPNM]
      ,[CCOMemberID]
      ,[MemberID]
      ,[CCOType]
      ,[RateCD]
      ,[Rate]
      ,[CurrentAge]
      ,[BirthDT]
      ,[Gender]
      ,[Language]
      ,[RaceEthnicity]
      ,[ZipCD]

Query plan is available in case that is helpful. https://www.brentozar.com/pastetheplan/?id=S1L0EMrdo