As for banning things in practice: forcing ISPs to do IP and DNS level blocking as a start, combined with fining companies or imprisoning their legal representation if they do not comply with national laws. If IP blocking doesn't work, there are things like SNI inspection that can do the trick.
If the business in question has no legal representation within the country, blocking payment providers and other services operating within the country from doing business with them is often an easy way to cut off access. This is probably not going to affect Element much, but if such restrictions come from a more economically influential trading bloc (USA, EU, etc.) international companies may be in more trouble.
An example of this is trade with Iran; in many countries there aren't many noticeable sanctions, but doing trade will put you on the naughty list of the USA and that can be a significant problem with the American influence on things like payment providers and the internet.
As for banning things in practice: forcing ISPs to do IP and DNS level blocking as a start, combined with fining companies or imprisoning their legal representation if they do not comply with national laws. If IP blocking doesn't work, there are things like SNI inspection that can do the trick.
If the business in question has no legal representation within the country, blocking payment providers and other services operating within the country from doing business with them is often an easy way to cut off access. This is probably not going to affect Element much, but if such restrictions come from a more economically influential trading bloc (USA, EU, etc.) international companies may be in more trouble.
An example of this is trade with Iran; in many countries there aren't many noticeable sanctions, but doing trade will put you on the naughty list of the USA and that can be a significant problem with the American influence on things like payment providers and the internet.