It is normal in public sector. I was offered a position in a public sector job and the supervisor gave me the keys to the office and lab and told me that due to hiring requirement blah blah, they had to put a new tender and post the position online for several days before they can declare me as the selected candidate. The contract will be delivered to me via post after the day they take down the advert.
While I felt immensely special and cool, but once I received the contract by post, one of my random friends called me o say that he needed a job badly and found this perfect opening and applied there, but he got rejected, whether I was interested to also apply for that position, the requirements looked like I would be the best fit. When he sent me the PDF, dang, it was the same job that was being posted for me and I was super sad.
I eventually did not sign the contract because the practice really felt immoral to me and recommended my friend instead. While my supervisor was super sad, because they had to go through a long process for that fake job advert, nonetheless he understood my stance and went ahead and called my friend again.
I believe these public institute jobs must post internal hires publicly to comply with certain regulations or something, but the practice is weird.