On 2 different Windows PC's, Win 10 Desktop Nvidia RTX4070 graphics card and Dell Inspiron Win 11 laptop, after starting GOG Space Engine once and closing it down, next time you start it there is no main menu and the initial graphics video is frozen. Also there is no sound.

Not sure how to supply log.

The log is called "se.log", a text file contained inside a "system" subfolder of the main spaceengine installation.
Assuming you're using GOG Galaxy client, the main spaceengine folder can be found by selecting the SpaceEngine program, then the "more" button on the top-right corner > Manage installation > Show folder.

The log can be uploaded here from a reply window, by using the "Add files" button below the input area.

A possible reason for this issue could be a damaged configuration file. From the spaceengine main folder, go into the "config" folder and delete "main-user.cfg", and delete the entire "cache" folder. They will be recreated next time the program is launched.