Hi @Nurkoyiz, welcome to the /e/ forum.
Edit, I think to a certain extent you are referring to the Document App within ecloud.global_apps_onlyoffice, but this is not the app shown in your image. I worded my explanation on the basis you are showing us a download from that app. Please correct me if I’m wrong !
I can get a similar result when I use the built in LibreOffice Viewer to open an OpenOffice produced .docx download. When I delete Data (see below) the app just fails to open the “unnamed” document.
However when the download is an OpenOffice produced .pdf the PdfViewer Plus fully opens the correctly named document.
You might check the App-Information in your image to see which app is misbehaving.
Often when an app fails like this the best first course of action (which I just did on both apps !) is to Clear storage. (There is a less robust action, simply clear transient data with Clear cache. Often one will Clear cache on an app that is storing its own settings – these settings would be lost with Clear storage.) These are found from
Settings > name-of-app > Storage & cache > Clear storage | Clear cache
Edit. Regarding delete; I expect either app to open a document Read Only, so I do not expect to see a delete option. I expect to delete the file (which you show within Downloads) using the Files app.