These seems to be an indication:

Or do you mean the number of potential pages impacted?
I.e. for templates also including the number of pages that transclude the template?

There are two different, unconsistent types.

Steps to reproduce:

Type 1:

1. create or edit Category:Foo
2. add some page to Category:Foo
3. RC shows:

Category:Foo (2 changes | history) .. (0) .. [Username (2×)]
(note the (0) which is an issue of T126428: [CatWatch] resets enhanced Recent Changes grouped bytecounter)

Type 2:

1. put some page into Category:Foo
2. put another page into Category:Foo
3. RC shows:

Category:Foo .. (0) .. [Username (2×)]
(note the (0) which is an issue of T126428: [CatWatch] resets enhanced Recent Changes grouped bytecounter)

The "(2 changes | history)" is missing.

I would actually suggest to close this and similar tasks in favour of T126851: [CatWatch] Find an unconfusing/specific way how to display CatWatch changes - aka rather than fixing bunch of confusing places, create a unique way of displaying which does not interfere with current edits and logs.

So normal when there is a single entry on the group view it looks like this:

A single catwatch entry looks like this:

Grouped edits normally look like this

However if the group only contains catwatch entries it currently looks like this:

The bug for this task can be seen as a missing change count in the last image.

Change 276503 had a related patch set uploaded (by WMDE-Fisch):
CatWatch grouped edits and number of changes

https://gerrit.wikimedia.org/r/276503

Change 276503 merged by jenkins-bot:
Adding number of changes info for grouped category changes

https://gerrit.wikimedia.org/r/276503