Project management while valuable, is not a unique skill set and there is nothing in the managing skill that requires a longer restraint clause.
The issue becomes one of knowledge gained while working on the projects that may be very commercially sensitive to your employer.
Suspect it comes down to what you will accept. The more senior the role, the more a court will put emphasis on your ability to negotiate your own contract terms.
There is nothing stopping you negotiating for a change. You may not be successful, but it comes down to your choice whether to accept their contract terms or move elsewhere. If you accept their terms, you may be able to argue later the restraint was unfair but it then comes down to the individual circumstances of your case and then it is up to a court to decide what is fair, not a lawyer.