What is the correct damage for Vicious Weapon?


While typing up my answer for Where are Vicious Weapons detailed? I noticed there’s an inconsistency with the description for Vicious Weapon between what’s written in the DMG and the SRD.

The DMG states:

When you roll a 20 on your attack roll with this magic weapon, the target takes an extra 7 damage of the weapon’s type.

Whereas the SRD says:

When you roll a 20 on your attack roll with this magic weapon, the target takes an extra 2d6 damage of the weapon’s type.

I checked the DMG errata and there hasn’t been a correction added there.

Has this been updated elsewhere and which text is meant to be the correct damage for Viscious Weapon: 7 or 2d6?

P.S I know the average roll of 2d6 is going to be about 7 anyway but that’s not the point.