Thank you for your prompt response.
I tried the actions you recommended, but after a while the layouts broke again.
I have found a temporary patch that has helped me to understand where the problem may be coming from, and it is related to the page templates.
If I select “default template” or “full width template” the problem still occurs. However, if I choose “minimal template” this error doesn’t occur anymore. This is a solution for static pages, but it doesn’t work for the news page because you can’t choose the type of template once you choose it as the default page for the posts.
I have to try to create a new page by selecting “minimal template” and then assign it as a posts page.