Curd clumps in yoghurt

I wanted to use this but once I started stirring the yoghurt I noticed tiny curds throughout the it, I tried tasting it but it’s plain so I’m not sure how to judge if it’s off, it tastes a little sour but I thought that’s how it’s supposed to taste? Also it smells fine too. The best before date us May 1st so that’s still a while before it’s supposed to “go bad” so I’m not sure I just need other opinions😭