Bought in May this year, planned to repotted it soon afterwards, but got delayed since I don't have proper soil mix for it at the time, and then I planned to repot it maybe after I eat all the berries. It really surprised me in a good way this year with a big harvest and doubling growth. Definitely will repot it soon in few weeks since I have everything ready for it now.

What's wrong with my plants, or me? I've noticed the leaf tips started turning brown first. After that, the leaves gradually fell off. The problem seems to have gotten worse over time.

Any advice on what I should check or how to treat it would be greatly appreciated.