This is our avocado tree:

https://imgur.com/gallery/nJLQa
I'm not sure how old exactly it is, but it's around / over a year approximately, and unfortunately it has some brown spots on the leaves.
Also I have already snipped off few other leaves where the brown spots were big.
My question is - does anyone know what could be the reason for these brown spots, and how to fix that?
Thank you very much in advance!
P.S. We are going to plant it in a bigger pot very soon.
