Metronome mark not aligning correctly

[Knute Snortum]

I think I have found a bug, or at least an "ugly" behavior.  Consider
the following code:

%%%
\version "2.22.1"

rightHand = \relative {
  \tempo "Allegro"
  a'''16->-4( g f c  a g f c  a g f c  \change Staff = "lower" a g f c) |
}

leftHand = \relative {
  \clef bass
  f,1 |
}

\new PianoStaff <<
  \new Staff = "upper" \rightHand
  \new Staff = "lower" \leftHand
>>
%%%

(see attached picture)

The metronome mark is aligned too low and collides with the accent
mark and the fingering number. Take out the slur and everything's
okay.  Same with the staff change.

So two questions:  1) is a bug? and 2) how do I adjust the metronome
mark's height?  Y-offset and Y-extent don't seem to change anything.

--
Knute Snortum