Good question.

First question is, where does the hydrogen come from? Most of it is reformed from natural gas, which still needs a fossil fuel as a base. Until we have a huge surplus of renewables or nuclear, I don't think it makes sense to use electrolysis to get it from water.

Second, it takes another big amount of energy to compress it, chill/liquify it, then transport it. To the point where one chart I saw put EVs at getting 3x more "work" out of the same electricity input than a similar car would get from hydrogen. For comparison, an EV can go ~30 miles on the energy it takes to create a gallon of gas from the feedstock, so there's that too.

Then, it needs to be stored and transferred under high pressure. We've all seen the dumb things people do putting gas in their cars, and that's easy. Imagine everyone trying to fill their own propane tank