Remove vertical space induced by substack

With the aligned environment one can split equations across multiple lines. When using substack, more space might be required by a line, shifting any subsequent line further:

begin{align}
  begin{aligned}
    F(M) = bigcup_{substack{x, y in M x neq y}} big{{x,y} mid& text{long condition 1},
  & text{long condition 2} big}
  end{aligned}
end{align}

Is there a way to remove or ignore the vertical space occupied by the substack (indicated by the red arrow)?

documentclass{article}

usepackage{amsmath}

begin{document}

[
F(M) = bigcup_{substack{x, y in M x neq y}} bigl{ {x,y} mid
begin{aligned}[t]
  & text{long condition 1}, 
  & text{long condition 2} bigr} 
end{aligned}
]

end{document}