Both numbers are correct, they simply count different things.

The catalogue row counts protocols. If an oracle shows 546, then 546 protocols name that oracle as their price source.

The list the click opens shows rows. And it groups protocol families: a brand running several versions of its protocol appears once instead of seven times. The versions can be expanded under the family row.

Some of those 546 protocols belong to such families, which leaves roughly 500 rows in the list. Nothing is missing, it is grouped.