Doesn't that swipe between desktops/workspaces/whatever? On that note, I have no idea how anyone is supposed to discover these gestures. I had the same problem when I had an iPhone for a few months (long story): I became afraid to swipe anything because I never knew what anything would do and the lag on the thing meant that some widget could show up under my finger without knowing (something I really dislike about reflowing and progressively loaded websites too). The floating dot thing was also way more invasive than a button too.
FWIW, I have animation time set to 0 on my Android phone to avoid these kinds of behaviors but given that the primary interaction was through them on Apple, it was unavoidable.
By default yeah, you need to disable that gesture (or set it to 4 fingers) and then enable 3 finger drag in accessibility settings under trackpad. Aside from 3 finger drag though these are all in the normal trackpad settings, it's pretty clear about what does what and all of it can be disabled.
This used to be a regular (non-accessibility) setting, not sure why they hid it away a few versions ago.
In system preferences there are videos demonstrating all trackpad gestures in the trackpad settings.
I think most issues people have with using the trackpad are due to the fact that the default is that you have to click the trackpad like a mouse button in order to perform a "click." Most people coming from Windows want to use tap to click and I think that is what leads to confusing results.
FWIW, I have animation time set to 0 on my Android phone to avoid these kinds of behaviors but given that the primary interaction was through them on Apple, it was unavoidable.