It can be a shock when you see the higher number on the scales, but fluctuations happen when you’re losing & when your weight is stable too . Fluid retention, constipation, hormones, just because our bodies can be weird can contribute. It could even be your scales - uneven surface, failing battery, etc.
I’ve posted this before but my scales read this a couple of months ago. It initially read more than 150kg - 3x my weight. So yes, heart palpitations & a second or two of thinking how the &**##$ did I put on that much weight before I regained my senses. Replaced the batteries which saw the 136kg weight but turned out the scales were dying.