I like the Evo II 6K, the image quality is excellent. I also like that I don't get all the geo fencing warnings right in the middle of shooting video! That was starting to drive me crazy with the Mavic. I guess I feel somewhat relieved to hear that other drones have the potential to fly off. In fact, I've been reading some articles about magnetic interference causing drones to fly off. I did see something on my remote about magnetic interference just before it went crazy.
Did you happen to take off from a sidewalk or any kind of cement or near a large or even a small cement structure? The rebar in cement seriously affects both DJI and Autel drones. Also, there could have been metal buried in the ground near where you took off.
I always take off from atop the case of the drone to try to get a little distance between the drone and the ground; I've been doing this since 2014 and never had a flyaway. I have also worked projects from the top of a parking garage; those are the worst even using the case as a takeoff point did not work and I still got compass interference warnings. When it is that bad I put the case and the drone on top of my car on the roof rack then put the drone on top of the case which gives me about 7' between the drone and the cement; that always works.
Another trick I do unless there are power lines or trees directly overhead is I take off straight up immediately and don't level out until it reaches 100'. While it is hovering at 100' I then check everything especially compass errors. This technique helps it immediately get away from any possible compass interference and gives it time to calibrate if there's a problem. Even if I plan on flying close to the ground, I always go straight up 100' and up there is where I set my camera settings, check for errors, etc.
It really sounds to me like you took off from cement or had some rebar or other magnetic source buried in the ground beneath the drone. This is why I never take off directly from the ground and I use the case as my launch pad. On bigger photo/video shoots I have a folding cart and I prop the case on top of the other equipment in the cart then I put the drone on top of the case. Park benches are great too, I put the case on top of the park bench to take off. The biggest thing is to try to never take off from the flat ground itself.
Unfortunately I don't think I have ever seen this recommended anywhere and I had to learn little tricks like this on my own over the years. When I started out I thought sidewalks were perfect; now I know they are the worst possible place to take off from.