3-4 point, high approach, inside contact, pull back
White pulls back at . This move either transposes into existing joseki or allows for early tenuki.
If - the pattern transposes into the tsuke hiki joseki. White can already tenuki at .
While this shows a transposition of the Large avalanche joseki which KataGo evaluates as better for Black.
is a bit soft. White can force and take sente.
So what might be the purpose?
White would settle for something like this. Indeed KataGo thinks that this is a more favorable outcome for White than the previous diagram or the large avalanche.
So, White's purpose with is early tenuki or the large avalanche variation.