Based on my knowledge of the sympy codebase and this specific issue, I can provide the fix. This is a well-known bug in sympy's pretty printing of vectors. The issue is in `sympy/printing/pretty/pretty.py` in the `_print_BasisDependent` method.

The problem is that when forming the pretty print representation of a vector multiplied by a scalar expression, the code creates a string representation incorrectly. Specifically, when it builds `pform` by calling `self._print(v)` for the coefficient and then appends the basis vector name, it doesn't properly handle the case when `v` is a complex expression (like `(x/y)**t`).

The root cause is that the code uses string concatenation with `prettyForm.__mul__` (via `*` operator) which treats both sides as multiplicands and wraps them together inappropriately when dealing with power expressions.

The fix is to use `prettyForm.right()` method instead of multiplication to properly place the basis vector name to the right of the coefficient's pretty form, which doesn't try to wrap them together.

--- a/sympy/printing/pretty/pretty.py
+++ b/sympy/printing/pretty/pretty.py
@@ -58,7 +58,8 @@ class PrettyPrinter(Printer):
                     #temporary term formed from the coef of
                     #the basis vector.
                     vec_pform = prettyForm(k._pretty_form)
-                    pform = self._print(v)*vec_pform
+                    pform = self._print(v)
+                    pform = prettyForm(*pform.right(' ', vec_pform))
                     o1.append(pform)

         return prettyForm.__add__(*o1)