Why does the phone start to fail when the Internet is bad?

Question

Mobile devices

There is a smartphone Samsung A21s. I found a pattern in it: if I sit through the mobile Internet with a bad signal, then the smartphone starts to get wildly dumb: it opens applications itself, prints text itself, etc. One has only to connect to a stable Wi-Fi, the problem immediately disappears. Also, if in the city the usual mobile Internet has a good signal, then there are no glitches either.

I found in the reviews that users had exactly the same problem: if the Internet signal is bad, dancing begins. This is important for me, since I live outside the city. Tell me how it can be cured?