How can a request from a client to a server be encrypted and not at the same time?

Question

Android

I don’t fully understand this, so the question arose, when the mobile application starts, it asks the server about the availability of updates, it naturally answers it, the problem is that I can’t understand what system is used to encrypt the data between them and whether it goes at all, the question and the answer always start with the same characters (at any launch of the application), but the remaining characters change at each launch, + in the response from the server there may be readable info right in the middle, for example, a link to the update, then I don’t understand at all if to encrypt, then everything is always different, and here a part is not encrypted, and always starts from the same thing. Can you explain how the client and server communicate here? Ps In the picture there is 1 request from the client, then a response from the server, there is no link here, but it was just in the middle of the response.