Okay, thanks for these answers. Is it fair to say that ARKit takes into account when the ARAnchor was initially added to the session and uses this timestamp to figure out how much to adjust the ARAnchor's position as the ARWorldMap is refined? I did some testing with ARAnchors the other day and found that in iOS 15 they do move an appreciable amount when you rescan the same area (as you suggested).

Thanks for this reminder. Quick question on that, in the past I had tried adding ARAnchors to coincide with the user's position at various points in time as they moved around an environment. I found that the transforms of these anchors were never updated during the tracking session (or maybe moved by a minuscule amount). Is there a way to use ARAnchors that increases the likelihood they will be moved during pose graph updates? From what I know about graph SLAM, It seems at a minimum you want to be able to communicate to ARKit that a particular ARAnchor represents the pose of the user at some point in time. In this case, if the graph SLAM ever shifts this position during its optimization, the ARAnchor could move accordingly. The issue I see is that there doesn't seem to be anyway to communicate to ARKit that the ARAnchor should represent the pose of the phone at some point in time (rather than just some arbitrary content at a particular location in space). Is there a way to use ARAnchors in a way that allows one to access the results of graph SLAM so that one can recover the pose of the phone at points other than the current frame (i.e., from some time point in the past)? Similarly, if I have some content that I'd like to place on a planar surface, what's the best practice with that? Should I create my own ARPlaneAnchor? Should I just store the coordinates of my object in the ARPlaneAnchor's coordinate system? Thanks in advance for any information. I have always struggled to access the results of the ARKit SLAM algorithm at the level of granularity that I'd like. Also, I'm having trouble adding line breaks, so my apologies on that.

Okay. I submitted this as a feedback item. The workaround mentioned by bprzemyslaw seems to work, although the behavior is inconsistent when used in conjunction with a paused ARSession (so far I can only get it to work reliably when I don't pause the ARSession). The other issue I see is that the workaround only will work with maps that were saved with this special origin anchor. If the map doesn't have this anchor, the workaround doesn't seem to be applicable (I tried a few strategies, but none have panned out).