@dimalifragis Thank you so much, I think I found that what increases it

@dimalifragis thank you, I see my daily backup size in server increases rapidly as the new users registered each day, that's why I wondered

Thank you, so welcome emails are sent only for confirmation

I couldn't find where to fix it in the setting

@robert I've cached all, That's the register page

@robert I use WP Fastest Cache, I excluded but it doesn't work or I couldn't do it, can you help me, please

Thank you, I think that I can't afford it by myself unfortunately But, ı will ask it again

I have already done it hours ago 😀 check my comment