I've heard previously that they go so far as saying the charges are against the property itself so the owner has no standing to sue the government which keeps them from ever determining the constitutionality of civil forfeiture.
This is generally how the cases are titled - U.S.A vs $200,000 US currency, for example. Here's a list of recent federal court cases where the defendant is "currency" [1]. You can also view publicly posted forfeiture notices, which give an indication of the magnitude of this problem, here [2]. But the owner can still attempt to get it back, it's just usually at a very high legal cost.
This is generally how the cases are titled - U.S.A vs $200,000 US currency, for example. Here's a list of recent federal court cases where the defendant is "currency" [1]. You can also view publicly posted forfeiture notices, which give an indication of the magnitude of this problem, here [2]. But the owner can still attempt to get it back, it's just usually at a very high legal cost.
[1] https://prnt.sc/jzcl8c
[2] https://www.forfeiture.gov