Funny you mention this as a drawback, while it's actually a strength of mono repo that is perfectly handled.
For a widely used library. Leave the argument. This argument could be defaulted to NULL, the function can be marked @deprecated and it can log a warning message that the argument has no effect (depending on the language). That's how to handle updates with backward and forward compatibility. No need to break user code.
That's a strength of a mono repo. It only lets you do the right thing. You can't ignore other developers in the company and break all their software.
In a typical multi repo, there is the luxury to change anything anytime, as often as a developer feels like renaming a variable or a parameter. Creating a ton of unnecessary work for other developers who have the pain to keep up. That is, if they ever attempt to upgrade any library, there is no benefit to upgrading and it's impossible to keep up with all changes going on in all libraries thus it's rarely done in practice. The more it's behind, the more work there is to upgrade, the less likely it is to be done.
For a widely used library. Leave the argument. This argument could be defaulted to NULL, the function can be marked @deprecated and it can log a warning message that the argument has no effect (depending on the language). That's how to handle updates with backward and forward compatibility. No need to break user code.
That's a strength of a mono repo. It only lets you do the right thing. You can't ignore other developers in the company and break all their software.
In a typical multi repo, there is the luxury to change anything anytime, as often as a developer feels like renaming a variable or a parameter. Creating a ton of unnecessary work for other developers who have the pain to keep up. That is, if they ever attempt to upgrade any library, there is no benefit to upgrading and it's impossible to keep up with all changes going on in all libraries thus it's rarely done in practice. The more it's behind, the more work there is to upgrade, the less likely it is to be done.