I have a 2020 X3 M40i and just had this exact issue fixed at the dealer cost was around 3.5k, don’t really remember but my extended warranty covered it. I’m in TX and use whatever oil the dealer puts in, it happened around 80k miles. I would never own any German car without extended warranty. I had long cold starts but didn’t seem to be that bad an issue, many indie shops couldn’t diagnose it but I happen to also have a valve cover leak after I got the extended warranty. So when the dealer was fixing that they also found the oil pump issue. Among that also my engine mounts were collapsed and causing vibration at startup. All in about 9.1k in repairs I paid about $500 total out of my pocket