[mrjavadseydi]

AsPivot::delete() calls touchOwners() before deleting a pivot without a primary key. MorphPivot::delete() is a copy of that method, but the call was never added, so a custom morph pivot with $touches doesn't touch anything on detach():

class Post extends Model
{
    public function tags()
    {
        return $this->morphToMany(Tag::class, 'taggable')->using(Taggable::class);
    }
}

class Taggable extends MorphPivot
{
    protected $touches = ['tag'];

    public function tag()
    {
        return $this->belongsTo(Tag::class);
    }
}

$post->tags()->detach($tag); // tags.updated_at doesn't change

The same setup with a regular Pivot updates tags.updated_at. Pivot rows with an id column weren't affected, because that path already goes through Model::delete().

touchOwners() was added to AsPivot::delete() in 2019. When #30229 later copied the deleting/deleted events into MorphPivot::delete(), this call wasn't included. This adds it in the same position. It does nothing when $touches is empty.