I do not think that it is the very fact of entering the exchange that leads to a fall in the value of the coin.
In each case, the effect is completely different.
And if the project has not received proper development and support from investors, then naturally everyone wants to get rid of an unnecessary asset as soon as possible and merge it on the stock exchange at any, even the lowest price. And vice versa, if a coin seems promising, new investors actively buy it when entering the stock exchange.