CircleMovement

using System.Collections.Generic;
using UnityEngine;

public class Movement : MonoBehaviour
{
    [SerializeField] private float _speed;
    [SerializeField] private Transform _target;
    [SerializeField] private Transform _prefab;

    private Vector2 TargetDirection => (_target.position - transform.position).normalized;

    private void Update()
    {
        Vector2 roundDirection = GetDirectionAlongCircle();

        float weight = GetWeight();
        Vector3 finalDirection = (1 - weight) * roundDirection + weight * TargetDirection;

        transform.position += finalDirection.normalized * Time.deltaTime * _speed;

        //Instantiate(_prefab, transform.position, Quaternion.identity);
    }

    private float GetWeight()
    {
        float t = Mathf.InverseLerp(2, 4, Vector3.Distance(transform.position, _target.position));
        float weight = Mathf.Lerp(0, 1, t);
        return weight;
    }

    private Vector2 GetDirectionAlongCircle()
    {
        Vector2 r = transform.position - _target.position;
        float angle = GetRotationAngle(r.magnitude, Time.deltaTime * _speed);
        Vector2 rotatedR = RotateVector(r, angle);
        Vector2 roundDirection = (rotatedR - r).normalized;
        return roundDirection;
    }

    private Vector2 RotateVector(Vector2 vector, float rad)
    {
        Vector2 right = new Vector2(Mathf.Cos(rad), Mathf.Sin(rad));
        Vector2 up = new Vector2(-Mathf.Sin(rad), Mathf.Cos(rad));
        return new Vector2(right.x * vector.x + up.x * vector.y,
                           right.y * vector.x + up.y * vector.y);
    }

    private float GetRotationAngle(float r, float chord) =>
        Mathf.Asin(chord / (2 * r)) * 2;
}