Bug: Blunder that is obviously not a blunder

I just reviewed the following game:


It flagged 31. ... Rxd6 as a blunder, stating

> Checkmate is now unavoidable. exd6 was best.

However, after either move it is mate in 2, a very easy thing to evaluate. There are no other legal moves so by any definition Rxd6 should not be a blunder. It seems there is a small bug in the evaluation logic.

Ah, this is even more interesting. After refreshing the blunder has now disappeared.
For a second I thought I was seeing things, but I did actually copy the above text and still have the screenshot.

It seems that the initial feedback is perhaps taking some shortcuts after which the final set of blunders is produced for future reviewers to have a more accurate view.