Hey friend, you are growing indoor and if there is no pests or insects in your tent, that could be due to accidentally damge the leaves at young age.I have many leaves damaged like that due to accidentally touch at young.They only come to visible when they are large.Happy Growing... ✌️
If you have a clearer photo, it's hard to make out what you want to show. Either way, you could check underneath the leaf to see if there's any pest; it's good to do an inspection both during the day and at night.