>>14277857For algorithms your best bet is to look for books in more advanced topics like randomized algorithms, graph algorithms, approximation algorithms, computational AG or NT, sublinear algorithms, etc. At the introduction level, you really only find computability and complexity theory to be presented formally.
In general the mathematical rigor and sophistication of TCS papers is very much dependents on the actual topic and ranges widely. That's one reason no one really bothers to write a book more advanced than CLRS at the introductory level -- it wouldn't be useful towards the goal of reading more advanced material. It's like asking why no one writes an introductory analysis book that assumes a strong background in abstract algebra. They are useful together down the road but at the introductory level not significantly.
