Dear Sasha_009,
Good days, thanks for querying in this forum. We’re happy to help you.
YES, you're absolutely right I get the same result as you. From our research we found out In SharePoint, collapsing multiple sections under a single header is not directly supported, especially when those sections have different layouts.
Thank you for providing the necessary information to help improve Microsoft products. I believe it would be beneficial to have the option to collapse multiple sections under a single header. However, currently, modern SharePoint only allows collapsing one section at a time.
- Please provide your feedback here so the developer team can look into it and make your suggestion a reality click here --->>Microsoft Feedback Portal
We apologize for the inconvenience. Microsoft always evolves according to user feedback, and we believe that the function you are referring to will be a reality in the future.
Thank you for your time and patience, we hope you have a nice day!
Sincerely,
Microsoft Moderator | Sophia