I noticed an increase of topics in https://leetcode.com/explore/learn/ such as arrays and linked lists.
I am really happy to see so many topics I can learn and get to solve problems about.
This post is a suggestion for 2 additional topics: graphs and dynamic programming.
Both those subjects are treated with care on MIT OCW 6.006 but a leetcode style (incremental difficulty with exercices from trivial to medium level) would be interesting in my opinion.
Those topics seem to be classics of interview questions. I believe these chapters would be both useful and popular.