How to DISABLE Keychain/Safari Password-Automatic Sharing across MAC devices

My business has company Apple ID Account that multiple office MACs are linked to.. we recently upgraded most of our devices (to the newer models) and somewhere in the process of migrating our systems, some setting was altered that merged all of the passwords we each had saved on our own individual device's Safari Keychain - we've always used the same Apple ID and this was NEVER the case before.

I double-checked the iCloud Settings on all of our devices and the 'iCloud Keychain' option is not selected for sharing on any of them.

Does anyone know why this would have happened all of a sudden? and, more importantly, how I can RESTRICT password sharing between each MAC from now on???

*We each have our personal logins saved on our desktops and we can't have all of our coworkers having access