I am having the same problems with after market replacements as well. My Airtex #4149 (made in Illinois 20 years ago) was leaking fuel.
My filter was a Re-man unit from Airtex as well. It may have started life as an original GM unit. Either way, it was from a long time ago when authentic OEM parts were rebuilt in the USA. Since cores have become scarce, bad copies are being made new but they're junk from the get go.
Then and Now did a great job on it.