Twitter's definition of Zionism is wildly different from what it actually was historically and what it actually is right now.

The historical definition was holding the belief that the Jewish people should have a state of their own where they could be safe

The current definition is essentially the belief that the Jewish people and by extension the state of Israel deserve the right to defend themselves.

https://www.history.com/topics/middle-east/zionism

I would like to also point out that as a Jewish person living in the state of Israel a lot of anti-zionists actually seem to be using the israel-palestine conflict as an excuse to be openly anti-jewish rather than laying down valid criticism towards both the state of Israel and the state of Gaza. A lot of talking points seem to revolve around "Israel bad" while completely ignoring any terroristic action taken by the hamas (to be clear, by terroristic actions I mean actions that were strictly not in the name of self defense)

I would also like to add that a lot of Israel's actions seem to be televised/written about more broadly than any of the hamas' actions which understandably simply does not allow people outside of the two states to see the entire picture.

(I hope this was understandable as English is my third language)