在以下示例中：

#include <concepts>
#include <cstdint>
#include <iostream>

using namespace std;

integral auto multiply(integral auto p_val_1, integral auto p_val_2) {
  return p_val_1 * p_val_2;
}

int main() {
  {
    float f{multiply(4, 3)};
    cout << "f = " << f << endl;
  }

  {
    float f(multiply(4, 3));
    cout << "f = " << f << endl;
  }

  {
    constexpr uint16_t i1{4};
    constexpr uint16_t i2{3};
    float f{multiply(i1, i2)};
    cout << "f = " << f << endl;
  }

  {
    constexpr int i1{4};
    constexpr int i2{3};
    float f(multiply(i1, i2));
    cout << "f = " << f << endl;
  }

  return 0;
}

gcc (Ubuntu 11.3.0-1ubuntu1~22.04) 11.3.0，在float f{multiply(4, 3)};中，报告

main.cpp:13:13: Non-constant-expression cannot be narrowed from type 'int' to 'float' in initializer list (fix available)
insert an explicit cast to silence this issue

在float f{multiply(i1, i2)};中，它报告

main.cpp:25:13: Non-constant-expression cannot be narrowed from type 'int' to 'float' in initializer list (fix available)
insert an explicit cast to silence this issue

在我对概念的理解（仍然）很差的情况下，不应该将multiply的结果分配给不满足std::integral要求的对象，但是使用float f(multiply(i1, i2));或float f(multiply(4, 3));就可以了。
有人能解释一下为什么吗？