is this a rumor, or true..?

no the top tiers are the ones who tend to make heavier cuts. Aphi, Pi Phi, and DG are always competitive, but Chi Omega and KD are more middle tier so they don't necessarily cut as heavy as those three. However, it would be an honor to be asked back to any of these houses, because they're all great

They may be doing better than past years and are making more cuts than they typical do (which seems to be the case). But overall actually PHA as a whole is retaining more girls this year which means every house is doing well!

Houses are required to cut a certain % of girls (with a little wiggle room) based on the last 3 years of recruitment data. More competitive houses must cut more PNMs and less competitive/new houses cut less. There are also some house-specific requirements that are private. The idea is to for each house to have the best chance to reach quota, not to be exclusive for the sake of being exclusive.

So if those three houses have been becoming more competitive, then yes, they would be making larger cuts than past years. No idea if it's true, but it's not something to worry about. Like a previous poster said, more women are going through recruitment and less women are dropping out, meaning bigger pledge classes for everyone (assuming a lot of PNMs don't drop to try to join KKG at the last minute). But the percentage each house cuts would be the same.