If I understood correctly, the Signal protocol generates a new key after every message sent and forgets the previous one. Telegram, on the other hand, renews the key only after 100 messages or one week. Thus, is there a certain attack window (1 week / 100 messages) with Telegram's protocol?
I think renew keys after a key generation is problematic because assume that key is already generated by the application. If somehow generate key pass through a function $H(x) = B(preImg(x))$. In simple language a function that somehow analysis key pattern and calculate $n$ pre-images of $x$.