These supports are not properly done.

Wood shouldn't be in contact with concrete. And the concrete is probably just sitting on the ground. It isn't a proper footing. Looks like a handy man special.

How serious is it? Who knows. You'd need a structural engineer to answer that. It's possible that these supports aren't doing much. Or maybe they are the things that are holding up the house.

Are you thinking of buying this house? Or do you already own it?

What's not properly done about this?

Piers come with wood as an integral part of them. How much contact is that?

Needs to be removed and re-done

What's not properly done? There are a variety of code violations and/or deficient construction techniques :

1. Non-pressure treated wood in direct contact with concrete

2. No steel brackets at top or bottom of post

3. Concrete pads do not appear to be of adequate size

4. Concrete pads appear to be sitting on surface of ground rather than being properly poured footers sunk into the ground

The leaning is the first symptom that this is going to get worse. The growth you refer to is the least of your worries. If you don't have these posts properly re-done, you're going to have all sorts of sagging floors and structural damage that will dwarf the cost of properly replacing these posts. And that's without considering any flood or earthquake events....