When Biden said Trump “proposes cutting a half a billion dollars of local police support,” he was referring to a
proposed budget cut of $465.8 million to the Office of Justice Programs, which provides grants to communities for different public safety issues.
One of the office’s hallmark programs is the Community Oriented Policing Services (COPS) Program, which was created by the 1994 crime bill that Biden wrote as a senator. The program provides hiring grants for community-based policing.
It’s unclear how much funding will be cut from the COPS program next year because Trump and Congress have yet to agree on a 2021 budget, but the office that it sits under is
looking at a 20% budget loss, from $2.3 billion to $1.85 billion -- about half a million dollars, as Biden said.
[ETA -- this must be typo for "billion"]