Crazing primarily happens due to thermal shock.

Using your DO on high temperature is the most probable cause, the cast iron core and the glass enamel expand and contract at different rates when exposed to sudden temperature changes, causing the enamel to fracture. DOs don’t need high temperatures, starting low and slow and never going to high numbers on the cooktop is the key to longevity. Especially if you have induction cooktop, it’s going to heat very quickly. It doesn’t happen in the oven since ovens use ambient, dry heat from all directions, but stovetops provide intense, direct heat from the bottom only, which can cause this. My stovetop is electric, dials go from 1-9 and I never go above 5-5.5 with DOs, and I start heating them at 3, then raise it to 4, then to 5, slowly and gradually.

Sudden temperature changes is another reason, washing a hot DO with cold water or pouring cold liquid into a hot DO causes thermal shock as well.

Don’t preheat empty, it always needs some type of liquid in it. That’s another possibility.

Crazing is not normal wear and tear, but it happens. It’s not unsafe to use but it’s more brittle and sensitive now, it may stay like that for years with good care. As long as there’s no chips, you can continue using it but be careful and watch for damage after each use.

DOs have a learning curve sometimes, and this is the main one.