Most of the problems are around searching a space for some solution or just simulating some state changes. Recent problems involved implementing a higher dimensional version of Conway's game of life[0], a simple arithmetic expression evaluator [1], or a simulator for a simple number game[2] e.g.
The most recent one[3] involves solving a jigsaw puzzle by using a simple backtracking search (or any number of other methods). It's a bit complex, but not reliant on a particular math trick.
The vast majority of the problems in advent of code shouldn't require any math tricks, though they're often complex and involved, particularly as the month goes on.
[0] https://adventofcode.com/2020/day/17
[1] https://adventofcode.com/2020/day/18
