My display creaks when I press it

Hello! I got a problem with my iphone xs max. I recently went outside for some shopping and i kept my phone in the backpocket. It was pretty hot outside and when i got back home i saw that the adhesive under the display had come out in the right top corner of the device. I was able to rub it off because it has “melted” into some kind of black slime. After a few weeks my display now creaks when i press it harder or when i whipe my display. Do i have to change the display or only the adhesive under it? Thank you!

​[Re-Titled by Moderator]