Unity player movement on moving planet

Question

I am making a game involving orbital physics. I was successfully able to implement this with a slightly modified version of Brackeys gravity tutorial https://youtu.be/Ouu3D_VHx9o, this is the code:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class gravity : MonoBehaviour
{
    public GameObject self;
    public Rigidbody rb;

    public Vector3 initialVelocity;
    const float G = 66.74f;
    public static List<gravity> Attractors;
    public bool isAttractable;

    private void Awake()
    {
        rb.AddForce(initialVelocity);
    }

    private void FixedUpdate()
    {
        //planets
        if (isAttractable == false)
        {
            foreach (gravity attractor in Attractors)
            {
                if (attractor != this)
                    Attract(attractor);
            }
        }

        //players, spaceships, astroids, ect
        if (isAttractable == true)
        {
            foreach (gravity attractor in Attractors)
            {
                if (attractor != this)
                    Attract(attractor);
            }
        }
    }

    void OnEnable()
    {
        if( isAttractable == false)
        {
            if (Attractors == null)
                Attractors = new List<gravity>();
            Attractors.Add(this);
        }

    }
    void OnDisable()
    {
        if (isAttractable == false)
        {
            Attractors.Remove(this);
        }
    }

    void Attract(gravity objToAttract)
    {
        Rigidbody rbToAttract = objToAttract.rb;
        Vector3 direction = -1 * (rb.position - rbToAttract.position);
        Vector3 Force = direction.normalized * (G * ((rb.mass * rbToAttract.mass) / direction.sqrMagnitude));
        rb.AddForce(Force);
    }

    public GameObject GetClosestPlanet()
    {
        GameObject close = null;
        float minDist = Mathf.Infinity;
        foreach (gravity attracor in Attractors)
        {
            float dist = Vector3.Distance(attracor.transform.position, transform.position);
            if (dist < minDist)
            {
                close = attracor.transform.gameObject;
                minDist = dist;
            }
        }
        return close;
    }
}

Then for player movement I used (and modified) Sebastian Lagues tutorial https://youtu.be/TicipSVT-T8, this resulted in this code for the player controller:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class playerController : MonoBehaviour
{
    public float mouseSensitivityX = 250f;
    public float mouseSensitivityY = 250f;

    Transform cameraT;
    float verticalLookRot;
    private Rigidbody rb;

    Vector3 moveAmount;
    Vector3 smootgMoveVelocity;
    public float moveSpeed = 15;
    public float jumpForce = 220;
    public LayerMask groundedMask;

    public bool grounded;

    public GameObject currentPlanet;
    private gravity playerGravity;

    private void Awake()
    {
        rb = GetComponent<Rigidbody>();
        playerGravity = GetComponent<gravity>();
        Cursor.lockState = CursorLockMode.Locked;
        cameraT = Camera.main.transform;
    }

    void Update()
    {
        currentPlanet = playerGravity.GetClosestPlanet();

        //camera
        transform.Rotate(Vector3.up * Input.GetAxis("Mouse X") * Time.deltaTime * mouseSensitivityX);
        verticalLookRot += Input.GetAxis("Mouse Y") * Time.deltaTime * mouseSensitivityY;
        verticalLookRot = Mathf.Clamp(verticalLookRot, -60, 60);
        cameraT.localEulerAngles = Vector3.left * verticalLookRot;

        //move input
        Vector3 moveDir = new Vector3(Input.GetAxisRaw("Horizontal"), 0, Input.GetAxisRaw("Vertical")).normalized;
        Vector3 targetMoveAmount = moveDir * moveSpeed;
        moveAmount = Vector3.SmoothDamp(targetMoveAmount, targetMoveAmount, ref smootgMoveVelocity, .15f);


        //level on planet
        if(currentPlanet != null)
        {
            transform.rotation = Quaternion.FromToRotation(transform.up, (transform.position - currentPlanet.transform.position).normalized) * transform.rotation;
        }
          


        //jump
        if (Input.GetButtonDown("Jump"))
        {   if(grounded)
            {
                rb.AddForce(transform.up * jumpForce);
                print("u jumped");
            }
        }




    }

    private void FixedUpdate()
    {
        //move
        rb.MovePosition(rb.position + transform.TransformDirection(moveAmount) * Time.fixedDeltaTime);


        //check if on ground
        Ray ray = new Ray(transform.position, -transform.up);
        RaycastHit hit;
        grounded = Physics.Raycast(ray, out hit, transform.localScale.y + 1.1f, groundedMask);
    }
}

Now for the issue, this systems works fine when the planet the player is walking on is stationary. As in there are no other attracting bodys in the system and the planet has no initial velocity. However if the planet is moving the player will bounce up and down uncontrollably and will not be able to walk a certain distance away from the planets farthest point from its direction of movement. Here is a recording of this: https://youtu.be/noMekosb7CU

Does anyone know what is causing the bouncing and walking restrictions and how I can fix it?

Some notes on suggested solutions that haven't worked:

-set the planet as the players parent object, same results

-increase players mass, same results

-set the players velocity to += the planets velocity, same results or player goes into infinity

Answer 1

For me it seems to be working "correctly".

Looking like your player is attracted correctly and when the planet moves, your player is quickly moving towards the planet.

I think you could temporarily assign the player as a child gameobject to the planet he's walking on and he should probably move correctly along the planet coordinates and not on global coordinates. (If it works, you could just always assign the player as a child gameObject to every new planet that he visits)