From the bill "IF THE PERSON MAKING THE VIDEO RECORDING IS
8 WITHIN EIGHT FEET OF WHERE THE PERSON KNOWS OR REASONABLY SHOULD KNOW THAT
9 LAW ENFORCEMENT ACTIVITY IS OCCURRING,"
Say a cop is kneeling on a guy's neck for nine minutes, and another cop is standing 8 feet from the killer cop, telling people to back up. The person with the cellphone is now 15 feet from the killer cop yet is in violation of the law because the other cop is clearly involved in law enforcement activity (that is, preventing bystanders from trying to stop the murder of a minority).
You scatter a few cops in a crowd no one can film within 30 feet of a police murder. The objection to the law is due to its vague and ill-defined term "law enforcement activity" and thus would need to be struck down by the courts, not because of the specific "eight feet". One is already not allowed to interfere in law enforcement activity, so the law is also not needed and is clearly designed just to prevent filming.