`#qedhere` misaligned in multiline equations

[lukasjuhrich]

Repro:

#import "@preview/ctheorems:1.1.2": *
#set page(height: auto, margin: 4em)

#let proof = thmproof("proof", "Proof")
#show: thmrules.with(qed-symbol: $square$)
#proof[
  For each $a_1,…, a_k in A$, we have $
  f (α^* (a_1, …, a_k))
  &= f( (π_(α_1), …, π_(α_n)) (a_1, …, a_k))\
  &=  f( π_(α_1)(a_1, …, a_k), …, π_(α_n)(a_1, …, a_k) )\
  &=  f( a_(α_1), …, a_(α_n)) #qedhere
  $
]

Ideally, the #qedhere would be aligned with the last line.