What causes disk space growth from Informatica load onto SQL Server?
Check some of the following:

-Free space of DB in prod before backup.  You might just have lots of free space in prod pre-reserved.  It used to be a best practice before IFI was introduced.  You'll still want to pre-allocate.

-Transaction Log size post recovery but pre-shrink by running DBCC SQLPERF (LOGSPACE) both times.  Maybe the transaction log doesn't have open transactions post restore and you are now checkpoint/shrinking it.  This would mean you might not be taking prod tlog backups and your recovery model is FULL.

-List the sizes for all of your tables in order of size post recovery and then against after shrink, then compare.