How can I recover deleted passwords and data from Keychain?

Hello, I use Apple services and products, specifically iCloud, on my iPhone and MacBook.

I decided that I wanted to disable the connection between iCloud Keychain and my MacBook. I went to iCloud and turned off the option that I assume disables the synchronization by using the green switch.

At that point, in Finder, I typed “Keychain” and went into the app labeled “Keychain Access.” On the left side, it has several sections, each containing saved passwords. In the first two, “Login” and “Apps,” I deleted the passwords by selecting them.

My goal was to prevent websites and apps that require login from automatically logging in on this laptop, as I was going to use it shared. I achieved this goal, but I later realized that my passwords have also disappeared from my iPhone. What can I do to restore them?

[Re-Titled by Moderator]