Reversing lag

Hi there I have just purchased a BYD Seal U dm-i. All is going well, however, yesterday I drove into a parking space, that had a slight forward slope. When trying to straighten up, I placed the car in reverse, placed my foot on the peddle, and nothing. The car started rolling forward about 1 foot, and 'then', with my foot on the floor, reverse kicked in and shot backwards... This happened every time I placed it in reverse whilst trying to manoeuvre? Can anyone let me know if this is 'normal' as it's bordering on dangerous. I was millimetres from hitting the wall in front of the parking space. Having had a google, the only thing that I can potentially think it might have been is the battery was on 23%, and it was mentioned that it could go into 'turtle mode' where there is a lag on most things to preserve battery power. However, surely, if it is that low, then why does the car not just put it in fuel mode??? Failing that, could it be a software issue??? Thx