プロセスが中断される原因は何ですか？

シェルセッションから抜粋した内容は次のとおりです。

brandon@Air ~ % brew upgrade rust

...

==> Pouring rust--1.75.0.arm64_monterey.bottle.tar.gz
[1]  + 76816 suspended (signal)  brew upgrade rust
brandon@Air ~ % fg
[1]  + 76816 continued  brew upgrade rust
[1]  + 76816 suspended (signal)  brew upgrade rust
brandon@Air ~ % fg
[1]  + 76816 continued  brew upgrade rust
[1]  + 76816 suspended (signal)  brew upgrade rust
brandon@Air ~ % fg
[1]  + 76816 continued  brew upgrade rust
==> Downloading https://formulae.brew.sh/api/formula.jws.json
##O=-#     #                                                                                                                                                                                   
==> Caveats
zsh completions have been installed to:
  /opt/homebrew/share/zsh/site-functions
==> Summary