It's remarkably intuitive and sensible if you remember that . in Zig auto-dereferences for field access and then treat `*` in this construct as field name denoting the entire object.
Ada does the same exact thing, except there you write `p.all` instead.
In any case, while the exact syntax may not be ideal, using a postfix operator for dereferencing is vastly better than prefix in practice due to typical patterns of use. There's a reason why you end up writing () a lot in C code with heavy pointer operations - the things they end up mixed with most often turn out to have the wrong kind of priority and/or precedence more often than not. Things are much simpler when everything is postfix and code reads naturally left-to-right.