That’s considered a mile stone at 6 months it’s called the tripod stance most babies won’t sit up completely unassisted until 8-9 months
My 7 month old still does this he just started sitting up right more but still enjoys the tadpole sitting
My baby does this I think they call it tadpole sitting it’s very common
My baby also did this at 5 months. I would hold his back and stomach to support him sitting straight up. Then I would let him lean forward and support himself with his arms. He will be 7 months soon and is sitting unassisted. He will occasionally still topple over if he jerks but he will sit up for 10+ minutes by himself. Hope this helps!