simsapa
Sources?
At times the Buddha could appear quite grumpy:
Then the Buddha said to Venerable Ānanda, “Ānanda, who’s making that dreadful racket? You’d think it was fishermen hauling in a catch!”
And Ānanda told him what had happened.
“Well then, Ānanda, in my name tell those mendicants that the teacher summons them.”
“Yes, sir,” Ānanda replied. He went to those mendicants and said, “Venerables, the teacher summons you.”
“Yes, reverend,” replied those mendicants. Then they rose from their seats and went to the Buddha, bowed, and sat down to one side. The Buddha said to them:
“Mendicants, what’s with that dreadful racket? You’d think it was fishermen hauling in a catch!”
And they told him what had happened.
“Go away, mendicants, I dismiss you. You are not to stay in my presence.”
“Yes, sir,” replied those mendicants. They got up from their seats, bowed, and respectfully circled the Buddha, keeping him on their right. They set their lodgings in order and left, taking their bowls and robes.
https://suttacentral.net/mn67/en/sujato
I have heard that on one occasion the Blessed One was staying near Rājagaha at the Bamboo Grove, the Squirrels' refuge. Now at on that occasion Ven. Pilindavaccha went around addressing the monks as if they were outcastes.
So a large number of monks went to the Blessed One and, on arrival, bowed down to him and sat to one side. As they were sitting there they said to him, "Lord, Ven. Pilindavaccha goes around addressing the monks as if they were outcastes."
Then the Blessed One told a certain monk, "Come, monk. In my name, call Pilindavaccha, saying, 'The Teacher calls you, friend Vaccha.'"
Responding, "As you say, lord," to the Blessed One, the monk went to Ven. Pilindavaccha and on arrival said to him, "The Teacher calls you, friend Vaccha."
Responding, "As you say, my friend," to the monk, Ven. Pilindavaccha went to the Blessed One and, on arrival, having bowed down to him, sat to one side. As he was sitting there, the Blessed One said to him, "Is it true, Pilindavaccha, that you go around addressing the monks as if they were outcastes?"
"Yes, lord."
Then the Blessed One, having directed attention to Ven. Pilindavaccha's previous lives, said to the monks, "Don't take offense at the monk Vaccha. It's not out of inner hatred that he goes around addressing the monks as if they were outcastes. For 500 consecutive lifetimes the monk Vaccha has been born in brahman families. For a long time he has been accustomed to addressing people as outcastes. That's why he goes around addressing the monks as if they were outcastes."
Then, on realizing the significance of that, the Blessed One on that occasion exclaimed:
In whom there's no deceit
or conceit,
his greed ended,
unpossessive, free from longing,
his anger dispelled,
his mind unbound:[1]
He's a contemplative.
He is a brahman
: a monk.
https://www.accesstoinsight.org/tipitak ... .than.html
Here an Arahant is still keeping certain character traits that others find rude. Then, of course, we have the rivalry between Ven. Ananda and Ven. Mahākassapa as shown in suttas like the Bhikkhunūupassaya Sutta. So, Arahants keep some remnant of their older personality even if that personality can be stern or rude. It seems Arahants can sometimes even clash with each other. My personal opinion is that members of the sangha couldn't match their idealised view of an Arahant with the actions of Arahants and so went on to develop a theory of the fallibility of Arahants.