Filming for the 6th installment of the hit Netflix series is underway, and according to The Sun, one scene, in particular, is expected to be met by pushback from Brits and others alike ... because, apparently, we'll see Princess Di's body.

The paper reports the scene in question depicts actress Elizabeth Debicki -- who plays Diana -- lying in an open coffin at what sounds like the morgue following her fatal accident in Paris. The Sun says actor Dominic West -- who plays Prince Charles -- comes in to look at her and breaks down in tears and hysterics, as do Princess Diana's sisters.

There's another controversial scene that's reported to have been shot -- which includes nurses and doctors trying to save Diana at the hospital ... totally drenched in blood. The Sun describes it as gory theatre, and jarring as well.

There are concerns it could retraumatize Charles, William and Harry -- and other members of the Royal family. The Sun reports some connected to the production feel Netflix went too far in what they've recreated for the small screen ... all in an effort to chase views.

It's unclear if Debicki was done up in injury-like make-up for the scene -- where she was asked to lie in the coffin and play dead -- but you gotta imagine the state of Princess Di's body wasn't in the greatest shape considering the horrific wreckage.

There's hope, it seems, as Season 6 draws near ... word of these scenes will drum up enough indignation that it might force Netflix to remove some of them, or edit them down.

Harry has said he watches the show, but noted ... he's well aware that it's mostly fiction. Will, for his part, has said he does not watch it -- other senior Royals have also either denied watching it or not commented altogether.