The fitness company is once again defending itself and clarifying the difference between reality and fiction ... this in the wake of a guy on the show "Billions" having a heart attack while riding a Peloton bike.

The new episode of the Showtime series aired Sunday, and it shows a character -- David Costabile’s Mike Wagner -- caving in on himself during a Peloton ride ... eerily similar to what happened to Chris Noth’s character for the series premiere of “And Just Like That...”

The difference now ... Costabile survives the ordeal onscreen, but Peloton is still in damage control anew -- issuing a statement to assure any current and would-be customers that ... their equipment is safe, and they’re not signing off on their brand being used to knock people off in scripts.

Peloton writes, “We get TV shows want to include @onepeloton to get people talking, but to be clear, we did *not* agree for our brand or IP to be used on @SHO_Billions or provide any equipment.”

They add, “As the show itself points out, cardiovascular exercise helps people lead long, happy lives.”

Of course, this is giving folks deja vu all over again following last month’s Peloton PR crisis -- when they had to scramble to address Mr. Big’s shocking death on ‘AJLT’ ... which they cleverly did, at first, with a funny ad in response that featured the deceased character.

Soon after, though, Noth got accused of sexual assault by a handful of women -- and Peloton yanked the ad altogether, fighting off a fresh round of bad press.