The recently committed WithinPrefixTreeFilter can sometimes match a false-positive due to the grid approximation technique. Some of this is normal. But if an indexed shape has any of its leaf detail levels "simplified" (removed) up to a higher level, then a false-positive match can occur that is a little too eager when one of those cells that were simplified-away don't intersect the query shape, and thus shouldn't be considered a match for this predicate.
Marking as "Minor" because it should be quite rare, and when it does occur, the answer (a match) will usually appear close-enough due to the grid approximation that it's not a totally inaccurate answer. I found this problem via extensive randomized testing. I want to fix it because it should make my new tests pass