Tldr people try to game image recognition, word filters, etc to increase visibility of their post on social media. It works.
People are slaves to the algorithm, even if they claim to not care. If you alter your post to increase visibility, you are playing by it's rules.
By censoring even potentially blockable words, not only are they improving the odds it will go to a wider audience, they get people to comment "why is that word censored/why is there a random dot/erase spot?" which drives up engagement stats, thus sending it to even more people.
oftentimes instead it’s a preemptive self-censoring to prevent your post from being shadow-banned / doing less well with the algorithm, for which there’s only very vague if any evidence that that’s happening, but vagueness is how these algorithmic sites work
Maybe more and more words will be blacklisted over time, slowly eroding the english language until nothing more can be said or expressed out of fear of spooking the advertisers. Nobody will be able to post anything, effectively reducing the platform to a useless, content-less desert filled to the brim with ads only. It will serve no purpose but to spread the consumer's gospel. It will happen slowly. Nobody in the general public will notice. Shareholder value has never been greater. The system works. Consume. Continue.
Most likely people with food allergies either knew that certain foods made them feel crappy (they just didn't know why), or just thought that everyone felt that way after eating those certain things.
Now, if it was an allergy that started after they got the job, that's different.