Since it's not a sequel to the whole collection, it doesn't belong in it.

That's definitely not the site standard though.

There are countless examples of collections including sequels that retcon previous sequels.

Just a few off the top of my head:

Halloween H20 retcons Halloweens 4, 5 and 6, following Halloween 2, and then Halloween 2018 retcons every other sequel including H20 and Halloween 2, only acknowledging the original.

Jaws: The Revenge retcons Jaws 3-D.

The Exorcist: Believer retcons all other sequels and follows only the original.

Terminator Genisys and Terminator Dark Fate each follow on from Terminator 2, ignoring intervening sequels.

Texas Chainsaw 3D ignores intervening sequels and follows straight from the original, and then Texas Chainsaw Massacre 2022 does the same thing again, ignoring Texas Chainsaw 3D.

This is very common.

Feel free to report incorrect collections.

I must say you're being very dismissive.

Are you saying the site standard is that a collection must always be a series of films that tell one continuous story without any retcons? Every additional entry must be in continuity with ALL of the previous entries?

Where is that written in the contribution bible? And if this is as widely known to be the standard as the tone of your replies suggests, then why is it that so many high-profile collections don't abide by it?

It would be interesting to see what reponse I'd get if I proposed splitting the Halloween collection into three separate collections and removing Halloween 3 from it altogether, which is what the standard you're suggesting would require.