5 yards. It would have been a flag in the NFL too.

"AI Overview

In the NFL, defensive backs (DBs) are allowed to make contact with receivers within the first five yards from the line of scrimmage, as long as it's legal contact. However, there are some rules that DBs must follow: 

Illegal contact

If a DB initiates contact with a receiver beyond five yards, it's considered illegal contact and results in a five-yard penalty and an automatic first down for the offense. This penalty is also known as the Mel Blount Rule. 

Maintaining contact

If a DB makes contact with a receiver within five yards and keeps holding onto them, they must release the receiver as they exit the five-yard zone. 

Holding

Holding the receiver is not allowed within the five-yard bump zone. 

Pass interference

If the ball is already in the air, illegal contact is called pass interference instead. Pass interference is a spot foul, which means the offense receives the ball at the spot of the foul. 

Illegal Contact | NFL Football Operations

Beyond the five-yard zone, if the player who receives the snap remains in the pocket with the ball, a defender cannot initiate contact with a receiver who is at...

NFL Football Operations

Bump and run coverage - Wikipedia

In the NFL, a defensive back is allowed any sort of contact within the 5 yard bump zone except for holding the receiver, otherwise the defensive back can be cal...

Wikipedia

NFL Defensive Penalties for Holding, Illegal Contact and Pass ...

Oct 5, 2021 — The NFL likes its flashy passing plays, so when a pass is thrown there are additional protections to anyone trying to catch the ball. Basically, both...

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Joonas Laitio

Illegal Contact vs. Pass Interference: Understanding NFL Penalties

Sep 9, 2024 — When It Happens. Illegal contact can only be called if the quarterback has not yet thrown the ball. Once the ball is released, the rule transitions t...

Refr Sports

Illegal Contact vs. Pass Interference: Understanding NFL Penalties

Sep 9, 2024 — Illegal contact is a five-yard penalty from the line of scrimmage, but it also results in an automatic first down for the offense.

Note: If a defender contacts a receiver within the five-yard zone and maintains contact with him, he must release the receiver as they exit the five-yard zone. If the defender maintains contact beyond five yards, it is illegal contact."