"Yeah – these travels have looked almost as stressful as people trying to get on planes in Afghanistan," one fan lamented.
Australian journalist Peter Ford accused the star of making "fast cash" on a product that "supposedly assists with dealing with pandemic stress" on Twitter.
While others said the Sydney-born star was "out of touch" as "no one is travelling except the rich and the elite".
"Whoever convinced you to post this BS should be fired, immediately. Travel is a privilege of the wealthy," one raged.
"Only celebrities will post about being stressed while on a giant yacht," another scoffed.
One asked if the paid promotional post was a wind-up, writing, "This is a joke right? Health gummies to combat the stress of luxury travel? I see the winner of most tone deaf and obnoxious ad of 2021."
Another refused to believe the post was legitimate, asking, "It seems like someone hacked Rebel Wilson's account."
Despite the fierce backlash to the post, shared on Friday, others praised Wilson and complimented her new appearance after losing more than 30kg since January 2020.
"You look amazingly happy," one wrote.
"I've never seen you so relaxed," said another.
It's not the first time Wilson has spruiked the US wellness brand, last posting about them in May as part of another paid post promotion.
Wilson has also flaunted her travels on social media, sharing snaps in recent months of herself in France, Italy, the UK, Mexico and various locations in the US where she currently resides.