support OnlyOffice xlsx

[DWay17]

throws Error: Unsupported format, password protected or corrupted if file was last written by OnlyOffice. Still in xlsx format.

[zazuum]

This is very few information. OnlyOffice have different branches, versions and architecture builds.
XLSX is a open standard format(compressed XML) so the issue could be with your locally(or in cloud) installed version of OnlyOffice possibly generating broken, corrupted files.

For test I was able perform search with xlsxgrep on random sample files edited with OnlyOffice Desktop Editors ver. 8.1.1.27 on Debian GNU/Linux 12 (bookworm) without any issues so I couldn't replicate the issue.

[DWay17]

I know. Its version ONLYOFFICE/8.0.1.31 running inside NextCloud. But I can't share the corrupt file. I created test files - but they were fine. I unzipped the xlsx and was able to format all xml files. So they are at least syntactically corrrect.

[zazuum]

Being able to unzip files doesn't guarantee file or files in the archive are not corrupted. I would address this issue to buggy OnlyOffice version or possible even Nextcloud if files are fetched/synced via Nextcloud. I tested online OnlyOffice demo with demo file and everything works without issues so I couldn't replicate the issue.
-> https://www.onlyoffice.com/see-it-in-action.aspx

I don't know which version is running in demo but I can see in changelog that many bugs in Spreadsheet Editor fixed in version 8.1.1.