How often do you update old file formats?
I was fortunate that some WordStar files I created years ago and originally were saved on 5.25″ floppy disks were eventually migrated to more up-to-date media and eventually placed on a hard drive. That folder of files was eventually dumped into a set of work-related items that was placed on the server we used at my former place of employment where they sat (after being migrated and updated numerous times) until I downloaded the files when I retired. I was lucky to still have them.
I was also fortunate that the format was readable by Google Docs with minimal difficulty in formatting (I originally used WordStar to create the files in the late 1980s).
That’s the difficulty with older digital files–keeping them on updated media and in a format that is readable. My personal preference is to avoid formats that are, for lack of a better word, “trendy” and less likely to have long-term support. Simple text documents with minimal formatting are also easier to read, but formatting text when transcribing documents does help to preserve some of its structure and “look.”
Don’t rely on just one “cloud” to back up your data and consider having personal back up sources that are in your possession or are not dependent on online access. Companies go bankrupt and servers go down.