Trigonometry, physics, set theory, graphs, path finding (all of these are quite a large set of fields, lots of algorithms and various levels of complexity from very simple basic understanding to formal mathematical proofs. You likely won't need to know it to the deepest level to be able to use it though but it can seem intimidating depending on your current mathematical level/ability/understaning/knowledge if you are just jumping in. Main thing to keep in mind is patience, it is a marathon, not a sprint and you don't need to be an expert in everything here.).

Generally anything with vectors is a good idea, normalization etc... (probably covered in Physics/Trig??)

Knowing about radians, degrees, slope of a line, distance between two points, angles, waves (sine waves etc... can be handy) are all pretty helpful for games in different scenarios.

I guess for AI learning about finite state machines can be useful but it's easy to get bogged down in terminology theory so find someone/some source that can break it down and make it easy to understand.