Try a hard factory reset. And hope that this behavior is not cooked in in the firmware.
So find a "trustworthy" source of a "decent" original dahua firmware, flash this on your "cheap chinese camera". There are two possible outcomes: either the devices starts working as a charm, either the device stops working completely. The distribution of probability is 0.01% versus 99,99%. BUT there is good news too: if this device gets killed-in-action, you will thank us later because this device can NEVER be trusted, so do NOT connect it to your network EVER again. Deleting your name/password is one thing, but it might be grabbing all your surfing habits, bank passwords, fridge keycodes and much more, and transfer these data to hackerds all over the world - or it might be part of a large botnet to infect Trump with Corona!
Up to you, better be safe than sorry, but if you pay peanuts, you'll get ... donkeys!
Happy Camming!
CC