Why is there little internal memory on Xiaomi Redmi Note 7?

Question

Mobile devices

Hello! I have a phone - Xiaomi Redmi Note 7. Today I took photos and videos while walking around St. Petersburg. Suddenly the phone gave out that I did not have enough memory. Although I filmed nothing at all. Now I have come home. I transferred the footage to the computer, and deleted everything on the phone - all photos and videos. Cleared the memory. It shows me that only 8 GB out of 64 are free. How so? Why is there little internal memory? I don’t really have any applications installed (only Telegram, WhatsApp, Instagram and a couple of applications from Yandex), but there is no music, photos and videos at all. Is there any way to free the memory? And, most importantly, what could clog the memory? This really surprises me ..

Thank you in advance for the answer!