Weird dots on small rectangle in lvgl8.3, or how to render a simplest rectangle?

The following boilerplate code is me attempting to draw 2d array of rectangles, for my starter project, but I’m not able to eliminate the 2 dots on every rectangle.
(The green rectangle is drawn afterwards, which is just a length 1 snake, and the green square also has weird dots, but the image is not that clear)

    playground = (Playground **)malloc(sizeof(Playground *) * row_size);
    for (uint8_t i = 0; i < row_size; i++)
        playground[i] = (Playground *)malloc(sizeof(Playground) * col_size);
        for (uint8_t j = 0; j < col_size; j++)
            playground[i][j].state = EMPTY;
            playground[i][j].rect = lv_obj_create(lv_scr_act());
            lv_obj_set_size(playground[i][j].rect, grid_width, grid_height);
            lv_obj_set_pos(playground[i][j].rect, j * grid_width, y_offset + i * grid_height);
            lv_obj_set_style_border_width(playground[i][j].rect, 0, LV_PART_MAIN);
            lv_obj_set_style_outline_width(playground[i][j].rect, 0, LV_PART_MAIN);
            lv_obj_clear_flag(playground[i][j].rect, LV_SCROLLBAR_MODE_OFF);
            lv_obj_set_style_radius(playground[i][j].rect, 0, LV_PART_MAIN);
            lv_obj_set_style_bg_color(playground[i][j].rect, GROUND_COLOR, LV_PART_MAIN);

The 2 weird gray dots on every rectangle makes me think of maybe its scroll bar, but apparently I attempt to disable with lv_obj_clear_flag(playground[i][j].rect, LV_SCROLLBAR_MODE_OFF); , and no avail.

If the rectangle size is bigger, the problem does not persist, it seems to happened when the rectangle is really small.

I was thinking to remove all style, and add it back manually, I search through the whole documentation, even read the source code, but I cannot find how do I even do this.

I attempt to draw a rectangle with canvas, and the ram overflowed. it might not be a good way to do it I guess.

The whole developer experience is just so painful with not much of information, or simply I suck at programming and getting the information I need.

Any way to draw a simplest small rectangle with plain color?

Additionally there is void lv_obj_remove_style_all(struct _lv_obj_t * obj);

Thanks for the reply, I genuinely appreciate this, the LV_SCROLLBAR_MODE_OFF now works.
One more follow up, If I were to use the void lv_obj_remove_style_all(struct _lv_obj_t * obj); , how to add the background properties?

Here’s the code I’ve tried:

lv_style_t style;
lv_style_set_bg_color(&style, GROUND_COLOR);

playground[i][j].rect = lv_obj_create(lv_scr_act());
lv_obj_add_style(playground[i][j].rect, &style, LV_PART_MAIN);
lv_obj_set_size(playground[i][j].rect, grid_width, grid_height);
lv_obj_set_pos(playground[i][j].rect, j * grid_width, y_offset + i * grid_height);

This does not work, anything I missed?

Yes - the keyword static. The style must persist beyond the scope of the function where it is used, i.e. static lv_style_t style;

adding static didn’t work, now there’s no rectangle showed on screen.

Since you have removed all other styling, you also need to set the background opacity in order to see the colour. I highly recommend reading the documentation. It’s rather good.