I had / have the same issue, immediatly after receiving the printer. Horizontal round objects are printed as ovals due to this. Bambu support studied the log files and concluded that there was unusual friction in the X-Axis (Carbon rods). They gave me two options, either send back the printer or to send me a replacement carbon rod unit. I chose the latter but after installing it (took me almost 5 hours!), including the new belts that came with it, the problem persists. Even after going through the cleaning and belt tensioning procedure multiple times. Printer is useless for now. I reopened my ticket yesterday so hopefully Bambu comes with a satisfying solution.
So my advice based on my own experience, contact support and take the option to replace the printer completely.
Hope this is a usefull answer for you.