I am really surprised no one brought this up in any of the forums or reddit yet (as far as I've seen), and it really scares me that this will not be changed.
At the moment, saving throws are being rolled at the start of a character/enemy's turn, opposed to how it should be. Tasha's hideous laughter even mentions "when it takes damage and at the end of its turns" at the bottom of the spell, which is actually how it was supposed to work.
As it is now, controlling spells such as hold person and sleep are really, really nerfed. When you cast the spell, the creature already makes its first saving throw (except for sleep, but it only lasts 1 turn), and if it also makes a saving throw at the start of its next turn, there is a huge chance the creature won't lose even one turn, and you've wasted your action and a precious spell slot.
I've done an entire playthrough trying to use control spells and another one with just damage spells, and guess what, the damage spells playthrough was a lot easier, even though I ran into a lot more combat encounters (since avoiding them grants no XP).
I'm not sure this is just a bug or it is intended to work this way. However, my beloved Larian Studios, if it is your intention to change this 5e rule (which doesn't make much sense because it is a rule that works very well in balancing spells), please reconsider it for the sake of your fans and players.
