0 K is like when there is 0 heat basically, while celsius isn’t. Imagine a unit for distance called “good” where 0 goobs is 100 m and 1 goob is 115 m. In that case the goob unit would behave differently than a meter when you multiply and divide because 0 of the units don’t actually correspond to “nothing” in a physical sense. That’s exactly how the Celsius scale is, with zero being placed somewhere arbitrarily, not at a physical zero.