Some devices taper off their fast charging faster than others. It doesn’t have to be at 80%. Just as an example you can see the charts in the charging review for the S24 Ultra here: https://www.chargerlab.com/charging-review-of-samsung-s24-ultra/. A fun fact is that since Samsung 45W tapers off so much there isn’t much difference compared to their 25W charging. The difference is 10mins at best. Sometimes the 45W can be just a hair slower even.
Some devices taper off their fast charging faster than others. It doesn’t have to be at 80%. Just as an example you can see the charts in the charging review for the S24 Ultra here: https://www.chargerlab.com/charging-review-of-samsung-s24-ultra/. A fun fact is that since Samsung 45W tapers off so much there isn’t much difference compared to their 25W charging. The difference is 10mins at best. Sometimes the 45W can be just a hair slower even.