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.
Actually we live in 2023 with all kinds of DPI / Great Firewall so every government considers citizens with an internet access as naughty children, with the corresponding appeal.
Governments make these things called laws. If you don't follow them they have people with boots and clubs that can take your money, lock you away and/or just rough you up a little when they take your phone to look what's on there.
They don't have to make it impossible to get the app, they might not even want to make it impossible! Because now instead of surveillance or not, dissidents (well, everyone) have the choice between surveillance and being a criminal that they can Protect and Serve(tm) at their discretion.
This is what the politicians mean when they say the laws of mathematics are below the laws of the country, and they're absolutely right. Don't bring tech to a legal fight, you will lose.
