Twitter isn't claiming of all its accounts less than 5% are bots. It is claiming less than 5% of their mDAU are. Without exposure to their methodology we are just speculating.
It is entirely feasible that at any point in time 20% of accounts are bots. It is whether they have counted them in their mDAU that matters.
It is entirely feasible that at any point in time 20% of accounts are bots. It is whether they have counted them in their mDAU that matters.