I'm having trouble finding out what to do with this error... here's the full message:

MacBook-Pro ~ % brew unlink php@7.4 && brew link --force --overwrite php@5.6
Unlinking /usr/local/Cellar/php@7.4/7.4.16... 0 symlinks removed.
Warning: Already linked: /usr/local/Cellar/php@5.6/5.6.40
To relink:
  brew unlink php@5.6 && brew link --force php@5.6
MacBook-Pro ~ % brew unlink php@5.6 && brew link --force php@5.6  
Unlinking /usr/local/Cellar/php@5.6/5.6.40... 25 symlinks removed.
Warning: Calling `sha256 "digest" => :tag` in a bottle block is deprecated! Use `brew style --fix` on the formula to update the style or use `sha256 tag: "digest"` instead.
Please report this issue to the exolnet/deprecated tap (not Homebrew/brew or Homebrew/core), or even better, submit a PR to fix it:
  /usr/local/Homebrew/Library/Taps/exolnet/homebrew-deprecated/Formula/php@7.0.rb:10

Warning: Calling `sha256 "digest" => :tag` in a bottle block is deprecated! Use `brew style --fix` on the formula to update the style or use `sha256 tag: "digest"` instead.
Please report this issue to the exolnet/deprecated tap (not Homebrew/brew or Homebrew/core), or even better, submit a PR to fix it:
  /usr/local/Homebrew/Library/Taps/exolnet/homebrew-deprecated/Formula/php@7.1.rb:10

Linking /usr/local/Cellar/php@5.6/5.6.40... 25 symlinks created.

I'm unsure of what "Calling sha256 "digest" => :tag in a bottle block" means in relation to Homebrew or exolnet, and trying to run brew style --fix php@x.x seems like it fixes a bunch of stuff but then I just get the same errors running unlink/link again, and eXolnet's GitHub is archived so I don't get the Open new Issue button... so I'm not sure where I'm supposed to report the issue.

I'm on macOS Catalina 10.15.7, on a MacBook Pro 2019, and I just updated Homebrew yesterday (it auto-updates anyway) to version 3.0.11-156-gbf79e3d.

Trying to Google search this gives Ruby answers or seemingly unrelated things, and I'm not familiar with Ruby nor those other things... I can't tell if the warnings are a red herring or what, and I'm not sure where to post about it. I can't even tell if I should even deal with these errors...

I simply need PHP 5.6, 7.3, and 7.4 running on my "new" Mac Catalina install (and my boss has recommended against Big Sur right now).