Here's the cream of the crop imo:
filipp.io's Cryptography Dispatches https://buttondown.email/cryptography-dispatches/archive
Fermat's Library fermatslibrary.com
The Popehat Report https://popehat.substack.com/
and I've been subscribed to Bruce Schneier's Cryptogram since before newsletters were cool ;) https://www.schneier.com/crypto-gram/
They also help me keep up with releases of the language, libraries and frameworks.
I miss blogs and RSS (with actual content, not just teasers.)
I wish there was one more like this which explains startup building (in terms of SWOT (https://www.mindtools.com/pages/article/newTMC_05.htm analysis))
https://whyisthisinteresting.substack.com/
It's a daily newsletter that's a sort of potpourri of interesting topics. They're pretty digestible, and they make it a point to avoid current events/politics. The writing is also very high quality.
Some of the top articles in leverage thoughts are: 1. Why you have to show your work to the right audience https://leveragethoughts.substack.com/p/cracking-the-who-you...
2. Why a technical person should not just pin their career on their technical skills alone https://leveragethoughts.substack.com/p/dont-hinge-your-care...
3.How leveraging ideas from others can be a superpowerhttps://leveragethoughts.substack.com/p/originality-is-not-t...
4. How to accelerate your career https://leveragethoughts.substack.com/p/early-career-tactics...
5. What Nikola Tesla can teach us regarding our first job https://leveragethoughts.substack.com/p/take-the-role-and-pr...
Linux: - https://ma.ttias.be/cronweekly/
Data: - https://nakeddata.org/