When creating a SQL function, querying Users table returns my session info, not my real Users table

I have a Users table, which is not empty. Following SQL snippet returns a different table from the one that I have in my database

create or replace function get_all_users() returns setof Users as $$
  select * from Users;
$$ language sql;

select * from get_all_users();

create or replace function get_all_users() returns setof Users as $$
  select * from Users;
$$ language sql;

select * from get_all_users();

create or replace function get_all_users() returns setof Users as $$
  select * from Users;
$$ language sql;

select * from get_all_users();

create or replace function get_all_users() returns setof Users as $$
  select * from Users;
$$ language sql;

select * from get_all_users();