Laravel 8: Base table or view not found - php

Question

I have two tables at db, one of them is named users which simply contains user information of website and the other one is tags which contains some hashtags that users can choose from them.
I also created a table named tag_user that can store the tag_id and user_id like this image:
(just like Stackoverflow that a user can select multiple tags such as php, javascript & etc)
So in order to make this relationship between these two, I added this to User model:
public function tags()
{
return $this->belongsToMany(User::class);
}
And also this one to Tag model:
public function users()
{
return $this->belongsToMany(Tag::class);
}
And here is the select option on blade, and users can select multiple tags from db:
<select class="form-control BSinaBold" name="skills[]" id="skills" multiple>
#foreach(\App\Models\Tag::all() as $tag)
<option value="{{ $tag->id }}" {{ in_array($tag->id , Auth::user()->tags->pluck('id')->toArray()) ? 'selected' : '' }}>{{ $tag->name }}</option>
#endforeach
</select>
Now as soon as I load the blade, I got this as error:
SQLSTATE[42S02]: Base table or view not found: 1146 Table 'dbname.user_user' doesn't exist (SQL: select users.*, user_user.user_id as pivot_user_id from users inner join user_user on users.id = user_user.user_id where user_user.user_id = 4)
So what's going wrong here? How can I fix this issue?
I would really appreciate any idea or suggestion from you guys...
And here is also the migration of tags & tag_user table:
public function up()
{
Schema::create('tags', function (Blueprint $table) {
$table->id();
$table->string('name');
$table->string('label');
$table->timestamps();
});
Schema::create('tag_user', function (Blueprint $table) {
$table->unsignedBigInteger('tag_id');
$table->foreign('tag_id')->references('id')->on('tags')->onDelete('cascade');
$table->unsignedBigInteger('user_id');
$table->foreign('user_id')->references('id')->on('users')->onDelete('cascade');
$table->primary(['tag_id','user_id']);
});
}
Thanks in advance.

Answer 1

As #aynber described in the comments:
In User model
public function tags()
{
return $this->belongsToMany(Tag::class);
}
And in Tag model
public function users()
{
return $this->belongsToMany(User::class);
}