Matthew 21:23 Jesus entered the temple courts, and, while he was teaching, the chief priests and the elders of the people came to him. "By what authority are you doing these things?" they asked. "And who gave you this authority?"
What does "these things" (ταῦτα) specifically refer to in Matthew 21:23?
In context of Matthew 21:23, the chief priests ( ἀρχιερεῖς) are questioning events that occurred in the temple (ἱερὸν) during the previous day:
He Overturned ( κατέστρεψεν) the seats (καθέδρας ) of those selling doves. [Matthew 21:12]
He Healed ( ἐθεράπευσεν) the blind ( τυφλοὶ) and the lame ( χωλοὶ). [Matthew 21:14]
We are to presume Yeshua (Jesus) of Nazareth returns to continue His temple reforms the next day based on Matthew 21:18 which states "in the morning (Πρωῒ ) then, having come back ( ἐπανάγων) into the city". - Then after returning to the temple in Matthew 21:23, Yeshua is questioned about His authority to do "these things" (ταῦτα ) specifically overturning seats as well as healing the blind & lame.