please, add a new db-level privilege SHOW CREATE ROUTINE so that the user with ALL PRIVILEGES on db level would be able to see all routines in that db

Update after discussing with Serg:
EXECUTE_ACL CREATE_PROC_ACL ALTER_PROC_ACL allow to get info about the routine, but SHOW_CREATE_ROUTINE_ACL should give the text.

This privilege related to PROCEDURE or FUNCTION or PACKAGE.

The effect of this MDEV is that one can give a user the 'show create routine' privilege, which allows the user to see the procedure text:
Example:

grant show create routine on *.* to user@localhost;

show procedure code test_db.sp;