There are a ton of channels that dig deeper in more general software and particulars: 1. Algorithms Live! for those that are into competitive programming
2. PapersWeLove for those that are into white papers and the research that underpins some of the systems that we use today
3. 3Blue1Brown for mathematics
4. ThePrimeagen for Vim and other software things
5. Gaurav Sen for digestible chunks of system design components
6. code_report for just programming. The author is going through Structure and Interpretation of Computer Programs (SICP) at the moment
7. commaaai archive for following George Hotz, founder and creator of comma.ai, a self-driving car company. He was a former Googler working on zero days (security)
8. Jon Gjengset for Rust. He's got a lot of great videos as an open-source contributor in Rust projects and was most recently at MIT doing his PhD
9. Bitwise is a bit old (last post was a year ago), but former Oculus lead dev teaching folks about compilers, simulators, FPGA-based hardware, and other low level topics from a practitioner
10. Two Minute Papers for quick high level hits/overviews of whitepapers
11. Engineer Man for great short introductions into various parts of the stack, scripting, Unix, and other abstractions
There are many more and recorded streams from other programmers teaching random things. There are tons of engineers on Twitch representing a multitude of companies like Lyft, CockroachDB, Netflix, and others working on open-source projects.
As a more experienced developer, I much prefer these channels over the ones listed, but my point is that the content is there when people actually search. The YouTube algos may not pick up all of them immediately and is most certainly more dominated by content directed at less experienced devs, but I much prefer some of this to the course recommendations that others are stating. Courses are really good, once you're convinced you want to do a deep dive into something, but most people do not finish MOOCs.