It doesn’t matter where in the world you are, the issue with forcibly deporting people is always the same: what do you do if the country you want to deport them to refuses to take them?
And the only answers I can see are let them go free in your country or keep them locked up indefinitely.
It can be difficult period. Why should any country take immigrants your country doesn’t want for any reason?
And “terrorist supporter” could be a very broad category. Are you a terrorist supporter if you support resistance against Israeli troops in Gaza? Because Israel and some of its allies would say yes.