I have it set to True, so they should not be able to teleport. However, for a bit now, they are able to teleport out of dome, airfield etc. It is set to true and the radius is 50 I believe.
Players able to teleport in monuments
Most of the monuments don't set a size so we have to pick a default. Airfield is one. Also, the logic of the config means it must be false to allow.
If they still can from the middle of the airfield then something is wrong. But, the airfield is larger than the default so it is possible to teleport from the edge. I may add a lookup table for these at some point. But for now try increasing the default.