Value of field ins null

In my OrderItem I have this:

   Filament\Forms\Components\TextInput::make('user')
                ->label('Ordered By')
                ->disabled(),

   Filament\Forms\Components\TextInput::make('user')
                ->label('Ordered By')
                ->disabled(),

   Filament\Forms\Components\TextInput::make('user')
                ->label('Ordered By')
                ->disabled(),

   Filament\Forms\Components\TextInput::make('user')
                ->label('Ordered By')
                ->disabled(),

The model OrderItem has this field:

    public function user(): BelongsTo
    {
        return $this->belongsTo(User::class);
    }

    public function user(): BelongsTo
    {
        return $this->belongsTo(User::class);
    }

    public function user(): BelongsTo
    {
        return $this->belongsTo(User::class);
    }

    public function user(): BelongsTo
    {
        return $this->belongsTo(User::class);
    }

In the database the user_id field has a value.
However the above TextInput return null. How can I print the name of the related user?
When I do

user.name

user.name

user.name

user.name I get

null

null

null

null