BIA is honestly not that good, just depending on how much you drink you can read as 5% lower than you actually are, there's a reason why most lifters will generally ignore all the non DEXA results. Yes it is possible to get low bf% but the person that did it would know once you get towards single digit it is something you mentally and physically feel. It's genuinely miserable and doesn't look good, when you see some somewhat built guy with ok definition but not super dehydrated they are probably around 15% so many people just don't know how much fat is needed to like fill out our body.