The article linked below blames Criterion, but I'd probably guess Disney (who now owns the movie) is the one who cut out the scene since Criterion doesn't usually censor the movies on their platform.
One Of The Most Classic Crime Movies Just Got Censored By Film-Loving Company
One of the greatest crime films in cinematic history is surprisingly being censored. Here's what we know about it!
www.giantfreakinrobot.com
A censored version of Gene Hackman’s classic 1971 The French Connection is currently in the Criterion Collection, as reported by Word of Reel. The censored scene in question, which doesn’t appear in the version whatsoever, contains two ethnic slurs in dialogue spoken by Hackman’s Popeye Doyle character. In the scene, Doyle says “You dumb guinea,” and “Never trust a [slur].”
Although the cut scene is minor, it is an interesting choice to censor it considering the context it gives Gene Hackman‘s character. Hackman plays an NYPD detective in The French Connection, and Doyle is frankly an unsavory person, so it’s not surprising that a cop from the 1970s would be racist. Taking the scene out probably makes Doyle seem like more of a good guy than he actually is.
There are definitely plenty of films that use racial slurs haphazardly, but in this case, it definitely seems like Gene Hackman’s character should be recognized as a bigot since his character is more of an anti-hero at best. Of course, this version of The French Connection could just be the one that The Criterion Collection has the rights to stream, so it may not necessarily be an intentional choice. Regardless, it is a pretty small thing and your experience watching the movie won’t likely change that much missing out on it, you might just miss out on a small bit of context for Doyle’s character.