My understanding is the housing is the same mold and product specification, dyed pink instead of red so that donated connectors can’t get resold.
(It makes literally no sense for APP to roll a custom mold or spring specification for our application from a business perspective)
I assume you’ve tested them. You might be seeing batch variation? What you’re more likely seeing is “low force” and “high force” contacts?
Low force: Anderson 1307 https://www.andersonpower.com/shop/powerpoler-75-pp75-sbr-50-silver-plated-wire-contacts.html
High force: Anderson 5900 https://www.andersonpower.com/shop/silver-plated-wire-contacts-6-awg.html
The last four years, 841 has bought exclusively from PowerWerx, who run the 590X high force SKUs as standard. https://powerwerx.com/anderson-pp75-sb50-loose-piece-contact
From years of batteries, chargers, etc, we have 40+ of these connectors in our shop. Some of the older ones are definitely easier to unmate, a lot of time I find stamped contacts, but once I rebuild the housings into new assemblies they’re right back up to normal range (“very difficult”).
Related: Some of our 9th graders didn’t have the grip strength to undo our SB50s until we added t-handles to the comp batteries, and removing sharp edges on the robot directly above the battery connector is a high priority due to a busted knuckle incident… maybe I should invest in some low-force contacts