Comment by Joker_vD

No, not really? From C++23:

    4) The result of E1 << E2 is E1 left-shifted E2 bit positions; vacated bits
    are filled with zeros. If E1 has an unsigned type, the value of the result
    is E1 × 2**E2, wrapped around. If E1 has a signed type and nonnegative value,
    and E1 × 2**E2 is representable in the result type, then that is the resulting
    value; otherwise, the behavior is undefined.

    5) The result of E1 >> E2 is E1 right-shifted E2 bit positions. If E1 has an
    unsigned type or if E1 has a signed type and a nonnegative value, the value of
    the result is the integral part of the quotient of E1 / 2**E2. If E1 has a
    signed type and a negative value, the resulting value is implementation-defined.

It's marginally more well-defined, sure, but not fully. The right shifts of negative numbers are no longer UB but are still an unportable mystery; and the left shifts of negative values are still outright UB.