One problem is in nomenclature, since not all anti-Catholics are “Protestant”, but some use the names “Reformed” or “Evangelical”, or “Non-denominational”. Hence you’ll see me use the abbreviation “n-C” for “non-Catholics” in posts a lot.
Naturally, it varies from person to person, (as does their personal interps of the Bible), but you have all stated it pretty well so far.
I personally consider it anti-Catholic (“a-C”) whenever anyone alleges that the Catholic Church is not a Christian denom since this is the implication of much of what we hear on here and other forums and it is patently untrue.
The other problem is in the term Christian, since many n-Cs use this term to mean those that have complied with their personal “way of salvation” (Ever seen the tract “Four Spiritual Laws” ?) and we Catholics use it to mean all those who express faith in Christ for their salvation. That’s where it gets hairy because of eternal security/OSAS/Calvinism, which define things differently and there are (again) variants thereof.
This is the reason that we often have so many posters here that seem bound and determined that they are here to “refute the errors of Romanism” and lead us all to a personal relationship with Christ.

That gets old PDQ…
I was talking about this recently with my wife who just came into full communion last Easter and voiced my thought that so many people seem to ignore the long, deep, and rich 2,000 year history of our faith during which the Catholic Church has answered every heresy to come along and how most “non-Catholics” attack the church with the same old same old things that we have either answered way early on, or else (in the case of non-Catholic denoms) over the last 500 years. I think one Bible verse sort of sums it all up for me.
Ecclesiastes 1:9: What has been is what will be, and what has been done is what will be done; and there is nothing new under the sun.10: Is there a thing of which it is said, “See, this is new”? It has been already, in the ages before us.
Pax vobisum,