When I started my career I quickly became convinced that meetings are the opposite of work. Now a large part of my career is hosting meetings. 😬
My biggest piece of advice to junior staff is: if you're not provided an agenda prior to a meeting, your attendance is not required. RSVP with Yes if it sounds interesting/beneficial and you have the time, otherwise Nope (or Tentative) your way out of it.
The obvious caveat is if that meeting is called by someone with role power over you. In which case: as they clearly don't respect your time, it's on you to (politely) ask them to provide an agenda. It may also indirectly train them to be less shit.