Yes, but depending on the code you’re working on that may be the case anyway even with a monorepo.

For example a web api that talks to a database but is deployed with more than one instance that will get rolling updates to the new version to avoid any downtime. There will be overlapping requests to both old and new code at the same time.

Or if you want to do a trial deployment of the new version to 10% of traffic for some period of time.

Or if it’s a mobile or desktop installed app that talks to a server where you have to handle people using the previous version well after you’ve rolled out an update.