Grafted Apple Trees......Red Tip Leaves?

Is there a reason for lot of my grafted apple trees the tips of many of the leaves appear to be getting red tint to them

Is this like lack of oxygen? or too much water?

They are in pots, but supposed to be breathable pots that decompose in 3ish years, although i did use garden soil vs potting soil don’t know if that was mistake. 1st year grafting, so not positive

Cultivar: Wolf River/Enterprise
Rootstock: Malus Dolgo

That is normal.

Yes, new growth of plants is often a different color than mature leaves. Reds (anthocyanins) are particularly common; it’s believed to confer some extra protection to the tender new growth.