in Oracle client 12.1 used from .Net if Stored procedure output parameter is varchar then its values are getting truncated
i.e., Bug 21616079
also fixed in Oracle client 12.2 https://docs.oracle.com/database/122/ODBCR/ODBCR.pdf
So we installed 12.2 but it did not help
is there anything else to do ?
Show that you are using 12.2 libraries with your .net code.