it's a plugin or a cvar

1-as i saw on some servers that dead & alive players can't see chat. like alive ct & t can see each chat and can't see ct & t dead players chat. and dead ct & t  can see each chat, but can not see alive  chat ct & t.

2-also there when i'm terror i can't spec ct, and when i'm ct i can't spec terror.

i'm asking about those, any help please?