I have a few writable sparse bundles that are located on a network share. I can mount and modify the content of these bundles from any pre-BigSur macOS release. However, after upgrading one of my macs to Big Sur it started mounting the same bundles in a read-only mode.
Surprisingly, when I copy over a bundle locally to that Big Sur mac and mount it from any local storage (internal SSD or a USB or TB drive) it appears to be writable.
Any ideas on how to fix it?