When you’re not invited to a meeting, it’s easy to point the finger and blame others for leaving you out, but that typically won’t get you the invitation. Ultimately the responsibility is yours to prove why you should be in the room.
The real currency of a consistent seat at the table is value. If the meeting organizer has left you out, they may not understand what value you bring to the meeting. Ask yourself what unique contribution you can make to the discussion. How will you advance the goal of the meeting?