Some are, yes. Their arguments are sometimes clever, and it takes a little doing to disentangle why they're wrong. For example, the argument that the flat plane is accelerating at 9.8m/s/s, which gives the same effect as gravity. Some people note that this would mean the Earth would soon be traveling faster than light, but that's wrong. At significant fractions of the speed of light, you no longer get the right answer by simply adding acceleration to how fast you were going previously from second to second. Rather, tt gets you infinitesimally closer to the speed of light without ever getting there.
However, this model doesn't account for why we get different acceleration from gravity when we go to higher altitudes. It also depends on Einstein's ideas of relativity, which flat earthers will often reject in other contexts.
But then there's the gate swinging guy, and it's not even clear what the hell he thinks he's showing.