I’ve played a backup on my local server, and was able to reproduce the issue.
Then, I’ve deactivated ALL plugins. Didn’t solve the issue.
Switch to an other theme and recreate the same blocks structure, and it was ok.
Back to the Twenty Twenty-Three theme, and played a lot with templates and blocks… And finally got everything working by changing from home to blog-home template for the startpage…
but I don’t understand the real reason for this issue. That’s weird.