One of the joys (or horrors depending on your POV) is that characters don’t have 1 meaning or one pronunciation. 漂 can be 1st, 3rd or 4th depending on the intended meaning, and is basically a perfect use case of why “tones are important”. This is what my popup dictionary looks like when I mouse over 漂:
But any dictionary will show you similar. Super annoying for learners but something you just have to get used to. It happens quite a a lot.
The HH team, for consistency just pick one meaning/pronunciation and stick with it. They pick that one based on which meaning has the most words that also use that meaning. The “elegant” meaning of 漂 used in 漂亮 has less uses so they went with the “to float” meaning of 漂 as their default one.
You just have to pickup the other meanings/pronunciations yourself outside of HH. When starting out I asked basically the exact same thing about why 还 being taught as huán not hái as in 还是.