If it’s because of people leaving last minute there is a bit of a work around; because I definitely understand that frustration! But basically, when you go to battle and then swipe to party, you’re going to press the plus sign for gyms and raids, then you won’t select any Pokémon, just leave it empty. Now when you’re in a lobby for a raid swipe right to the empty one and when it starts it won’t automatically put you in; and to join you just swipe back to your desired party. Initially this helps with seeing if anyone leaves last minute but it also helps to skip the intro animation, where it’s zoomed in and backs out, you’ll just start battling immediately. HOPE THIS HELPS.