The mother of three recently posted bikini pics with the TikTok star.
While Rae called the pics "a dream" and Kylie Jenner commented on the post with the fire emoji, others weren't complimentary.
"This friendship still weirds me tf out," one person wrote, with another adding, "fr she's 41 and she's hanging around with 19 year olds in swimming pools."
"Do you suggest a better place?" Kardashian responded, according to a screenshot posted by Comments By Celebs. "I'm looking for ideas..."
ET's Katie Krause spoke to Rae earlier this month, and the TikTok star said that friendships aren't "anything to really judge people on."
"At the end of the day, I think friendships are just what you make them. What you have, like the time you spend with them, the things you enjoy doing," she said. "And if you have things in common, it just makes sense. I don't think that's anything to really judge people on. I feel like friendships can range from any age and I feel like everyone can relate to people in different ways."
"Kourtney and I just happen to have a great friendship, which is really fun," she continued. "She's been a great person to have in my life. She said in my YouTube video that I had great energy that she liked to be around. I think she has great energy as well and she has so much experience in her life that I can really just look at and kind of learn from."
Watch the video below for more on the pair's bond.