Cluster munitions has a clear definition. It acquired a clear definition when the treaty was drafted. Cluster munitions release a … cluster (group) of smaller munitions that themselves explode on impact:

conventional munition that is designed to disperse or release explosive submunitions each weighing less than 20 kilograms, and includes those explosive submunitions. Submunition is a conventional munition that in order to perform its task is dispersed or released by a cluster munition and is designed to function by detonating an explosive charge prior to, on or after impact.”

Fragmentation munitions break apart and the fragments cause death and destruction.

If someone claims that she’s seen cluster munitions that were outlawed, she’s claiming to have seen cluster munitions that were outlawed, not fragmentation munitions. We may not like either, I certainly don’t, but one type is out of use in signatory countries and another type is not.

The picture she’s used it’s actually not even munitions, it’s fuzes, ie the thing that makes munitions detonate.

And in full detail, cluster munitions are still “legal” in signatory countries, provided the submunitions self-detonate after a time. The Oslo treaty was designed to prevent civilians, children especially, picking up unexploded submunitions. It wasn’t designed to prevent death and destruction in a military target.