Why is my overlocker chewing instead of cutting?

A ragged edge with threads hanging off it means the blade is not cutting cleanly. In most cases it is the lower blade.

Replace the lower blade first. It does most of the work and is usually the cheaper of the two. People habitually replace the upper blade because it is the visible one, spend the money, and find nothing has changed.

Check the blade engagement. The upper blade should just overlap the lower one. If the machine has been knocked or the blade recently changed, the overlap may be wrong. The manual will show the correct position.

Then rule out the other causes of a ragged edge, because not all of them are the blade.

Too much fabric being trimmed. Feeding a wide strip into the cutter overloads it. Trim closer to the finished line first if you are removing a lot.

Lint packed around the blade area. An overlocker generates offcuts continuously and the waste packs in around the mechanism. Clean it every session.

Wrong differential feed setting for the fabric, which stretches or bunches the edge as it is cut so the cut line wanders.

A blade is a consumable, like a needle. If you sew regularly, expect to replace one occasionally and do not treat it as a fault with the machine.