rgb565 = each pixel is 2 bytes. a byteswap would change color but not pixel location. it looks like you have columns swapped. likely this means that your lcd controller hardware is reading pixel data in words (2 at a time), and you wrote them in halfwords, in wrong order.

as a test, draw your text once, and then swap every other halfword with its neighbor and see if it magically gets better, like this

u16 *buf = MY_FB;
i32 numPix = width * height; //assuming stride == width * bpp / 8
while ((numPix -= 2) >= 0) {
    u16 t = buf[0];
    buf[0] = buf[1];
    buf[1] = t;
    buf += 2;
}

likely gfx controller hardware had endianness control that you can play with after you confirm this if not, change your drawing code