Currently

select soundex('TOM'), soundex('tom')

is leading to T500 and t500.

The result should be uppper case, as you are referring to MS-SQL in the code anyway: https://learn.microsoft.com/en-us/sql/t-sql/functions/soundex-transact-sql?view=sql-server-ver16