Depending on your direction. Theoretical economics can be done very hard and needs deep knowledge (see Yuri Sannikov, Jan Coetzee, Emmanuel Fache, Ivan Warning, Darrell Duffy; ; Measurement is common, such as Yacineait-Sahalia, Victor Chernozhukov). However, most theories do not need to use particularly deep mathematical tools, only need to know measure theory, functional, probability and stochastic process, and most paper mathematics can be understood. In fact, many difficult articles are often difficult not because they have deep mathematical knowledge, but because they use their own set of very complex game theory and tools (see Juuso Toikka, Andrzej Skrzypacz, Ilya Segal and other articles. And the mathematics used in their articles is basically not more than measure theory and functional, but it is very complicated).

In addition, theoretical economics is now slowly fading out of the mainstream, and now the mainstream is to run data directly. If you do this, you don't need any knowledge of mathematics. As long as you know calculus, linear algebra and basic probability statistics, you can handle almost anything.