Yes, this is present on many exchanges to attract users, but they do not explain the details enough to entice new users.
I remember that when I registered on the bybit.com exchange for the first time, I got a bonus. I don’t remember how much it was, maybe $200 or $100. I don’t remember exactly, but when I tried to withdraw it, they told me that it could only be used in futures trading and could not be withdrawn.
This means you can trade Future with this bonus, and if you get profits, you can only withdraw the profits.
People must realize that no one is handing out money for free. There are always additional conditions, where the "house" always wins. Certainly putting the mark "free" next to any offer makes it much more attractive.
I see that lately, Bitget is a lot more aggressive with promotion (at least on Bitcointalk), also a lot of
user spam shilling about this exchange. I don't like such an approach, but I suppose it will have some effect