whenever a recording is interrupted, it is usually gone.
it is a long shot, but you can try going into Apple Menu > Finder > Go > Go to Folder.

and in the resulting window, type in "~/Library/ScreenRecordings/" without the quotation marks.

but there might not be anything in there.
and as far as why the recording was stopped unexpectedly, what location are you using as your "save to" location? I have, in the past, encountered issues with longer recordings stopping / not saving unexpectedly whenever I have selected anything other than "desktop" as my "save to" location. this has been especially true when "save to" is set to an external drive. so I now use "desktop" as my "save to" every time and afterwards I move them to my desired location manually. I haven't had an issue since.