On Wikipedia, there is a fairly complicated timeline chart of the various LibreOffice variants [1]. Same article also says

> Ecosystem partner Collabora uses LibreOffice as upstream code to provide a web-based suite branded as Collabora Online, along with apps for platforms not officially supported by LibreOffice, including Android, ChromeOS, iOS and iPadOS.

[1] https://en.wikipedia.org/wiki/LibreOffice#History

I was also curious. It says this in about the middle of the homepage:

"We love LibreOffice. We are privileged to be the largest code contributors to the codebase, Collabora employs several founders of The Document Foundation, and many of the top committers. We offer a Long Term supported product based on LibreOffice, branded as Collabora Office Classic, and are deeply grateful for and acknowledge many skilled community contributors we work alongside, as well as the incredible range of features that LibreOffice code enables."

I think - not sure - that

* Collabora Online is rebranded, and hosted, LibreOffice Online

* or rather - LibreOffice Online never really existed and it was always Collabora Online Development Edition (I cannot find any LibreOffice Online that's not just Collabora Online Development Edition)

* Collabora Office for Desktop is Collabora Online, packaged as a desktop app

* Collabora Office Classic is just rebranded LibreOffice

* Collabora (the company) is one of the biggest contributors to LibreOffice

All of that is true. Collabora has put a lot of time and money into LibreOffice.

Also didn’t these guys buy Zetaoffice?

Yes, you're talking about Thorsten Behrens, one of the founders of The Document Foundation. His German company, Allotropia, merged with Collabora Productivity in 2025.