Some Glide features require file hosting. For example, when you upload files in the image or file picker and when you fill out the signature component, Glide stores that file online, and this counts against your storage quota.
You can learn more about files and quotas over at pricing.
Uploaded files will eventually be deleted if they aren't used for a long time.
"Being used" means that there is a link from your app to the file in a table. So as long your app links to a file somewhere in your table, Glide will not delete it (assuming your team is within your plan's storage quota).
If a Glide-hosted file is referenced in a row and that row is being used in an app—it will not be deleted
If a Glide-hosted file is referenced in a row, but the team is affected by quota overages—it may be deleted after 21 days.
If a Glide-hosted file is referenced in a row, but that table is not used in any Glide app—it may be deleted after 21 days.
Deleted files can be reinstated for up to 21 days after removal by putting them back in a visible row.