I think he said the law (or this particular asylum provision or whatever) has been in place since 1990s, but I may be wrong, I wasn't really listening to the debate just saw some clips here and there.
Re-watching I think you're probably right, he was talking about the
laws put into place in the 90s, which Vance was saying are being streamlined through an app created in 2020 and it seems like they are now able to grant this status at a higher/faster rate.
https://www.pbs.org/newshour/politics/watch-cbs-cuts-vances-mic-during-fact-check-on-immigrationCBS essentially made the statement that they are legal immigrants in Springfield after Vance (and I think Walz as well) had discussed them, Vance interjected to explain why they are called legal, and the explanation was the CPB one app and how it was being used to streamline the parole/asylum status, to which Walz said the "laws" were established in the 90's, Vance then says the app has not been in the books since the 90s and that Kamala created it, then mic is cut.
It's hard to say who is responsible for this app, I don't know how the organization itself runs but there were changes in commissioners for the US Customers/Border while this app was apparently being developed, I'd have to guess whoever is in control of it
at any given time can pick and choose how easily they want to approve applications.