TLDR version: publish TILs (Today I Learned) since then there's no pressure to say something new - just write about a thing you just figured out. And write about projects that you have done.
This advice is quite dangerous. For senior tech leaders disclosure of what they are working on often leads to disclosure of what a large part of company is working on. Even if company leaked information on what you are working on adding to it in your blog is not only about NDAs. Even if you own your company or startup and have a right to disclose you can cause damage. Even if your project is 'boring' disclosing information is potentially affecting company future outcomes.
Ofc one can have his own pet projects and only blog about them. But in the world where a cat tiktok account was allegedly used for spying there is no such thing as private tech blogs anymore.
At a couple of companies I've maintained an internal tech blog (e.g. using Confluence) so that I can write about internal projects in a private-to-the-company way.
TLDR version: publish TILs (Today I Learned) since then there's no pressure to say something new - just write about a thing you just figured out. And write about projects that you have done.