I haven't been following the Mavics but you'd have to look at the individual incidents before drawing any conclusions.
Why are they "flying away"?
I would suspect that they aren't really flying away at all but are subject to the same kinds of user errors that cause people to claim that their Phantoms "flew away".
The usual causes are flying downwind up high in strong winds, screwing up compass calibration, flying behind obstacles etc.
The Mavic attracted a huge number of new flyers with no drone experience.
And just like Phantoms, the ease of use causes some to get too adventurous too early and fly beyond their abilities.
In most cases with lost Phantoms, it's proved to be the operator that wasn't so reliable rather than the aircraft and it's probably the same with the Mavic.