Any ability that's waiting to go on the stack before the instruction to end the turn will not go on the stack. Triggers that trigger while you're ending the turn will go on the stack during the cleanup.
For instance, if you have a Sphinx's Tutelage on the battlefield and resolve Day's Undoing, the Tutelage would trigger. But since the turn ends, those triggers from the Tutelage will not go on the stack. But if your opponent has a Megrim and a Locus Miser (to reduce your maximum hand size) on the battlefield and you resolve the Undoing, Megrim's triggers will go on the stack when you discard during the cleanup step, since those triggers happen due to the instruction of the turn ending.
Nathan Long
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