Implicitly deleted special functions with std::chrono::time_point

I have some code like this

#include <chrono>
using std::chrono::steady_clock;
using std::chrono::time_point;

class MyClass
{
public:
    MyClass() noexcept = default;
    MyClass(MyClass const&) noexcept = default;
    MyClass(MyClass&&) noexcept = default;
    MyClass& operator=(MyClass const&) noexcept = default;
    MyClass& operator=(MyClass&&) noexcept = default;
private:
    time_point<steady_clock> timestamp; 
};

int main() {
    MyClass myObject;
    MyClass myOtherObject(myObject);
    return 0;
}

Trying to compile it results in

prog.cpp: In function ‘int main()’:
prog.cpp:18:10: error: use of deleted function ‘constexpr MyClass::MyClass()’
  MyClass myObject;
          ^~~~~~~~
prog.cpp:8:5: note: ‘constexpr MyClass::MyClass() noexcept’ is implicitly deleted because
its exception-specification does not match the implicit exception-specification ‘’
     MyClass() noexcept = default;

But compiles fine if I remove the noexcept specifier for the default constructor:

MyClass() = default;
MyClass(MyClass const&) noexcept = default;
MyClass(MyClass&&) noexcept = default;
MyClass& operator=(MyClass const&) noexcept = default;
MyClass& operator=(MyClass&&) noexcept = default;

So I have 2 questions:

• How come time_point's default constructor isn't noexcept? I mean, as far as I understand it only contains an integer of some type representing the time since epoch, which is supposed to be 0 for the default constructor if I believe cppreference
• Why does removing noexcept from only the default constructor work? If the compiler says that it had generated MyClass() and not MyClass() noexcept and therefore deleted it, it should be the same for MyClass(MyClass const&), right? But the compiler lets me do the copy without complaining here...