2D Character Movement Collision Problem

Hi guys, I'm currently trying to create a Physics-based 2D Platformer but I have encountered the following problem: My world is made out of a lot of instatiated prefab blocks which connect seamless (they're in a rectangular shape on which's top the player spawns). They have only a BoxCollider, SpriteRenderer and of course a Transform component attached. My player has all these, an additional RigidBody2D and my Player-Script. When I try to move my player at first everything works, but after a while and only after turning for the first time there appears something like an invisible barrier that stops me from going back but I still can go into the other direction. Since manually decreasing the "problem - block's" scale solves it (but only for that single block) it seems like it has to do with the player somehow colliding with the blocks' box colliders instead of "floating" over them.

How can I fix this or is this an entirely different problem?

Here is my player-movement script:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class Player : MonoBehaviour {
 
 
     public float speed;
     public float maxSpeed;
 
     private Rigidbody2D rb2d;
 
     void Start () {
         rb2d = gameObject.GetComponent<Rigidbody2D> ();
     }
 
     void FixedUpdate () {
 //Sideways Input
         float h = Input.GetAxis("Horizontal");
 
         rb2d.AddForce((Vector2.right * speed) * h);
 
         if (rb2d.velocity.x > maxSpeed)
         {
             rb2d.velocity = new Vector2(maxSpeed, rb2d.velocity.y);
         }
         if (rb2d.velocity.x < -maxSpeed)
         {
             rb2d.velocity = new Vector2(-maxSpeed, rb2d.velocity.y);
         }
         }
 }

Thank you in advance!