Autosave used to also save a ztl alongside the zpr, but now it does not. And loading the zpr after a crash pretty much is nothing - no geo, none of the work I did is saved. This makes Autosave during sculpting a non-issue, as none of the work I did before the crash actually saves.
Is there any way to get 2021.5 to Autosave a ZTL instead of a ZPR?
Hello @Valandar,
Autosave saves ZPRs, and I’m not aware of it ever having done differently. Sometimes in the event of a crash, a ZTL will be saved as a recovery file.
A tool can easily be extracted from any ZPR with the Tool> Load Tools from Project function.
A ZPR saves far more of your work than a Ztl file does. Ztls only save the active tool, and a limited selection of features that might apply to it. ZPRs save your entire scene, and all tools loaded into it.
A recovery file saved during a crash is not being saved under ideal conditions, and should not be relied upon to save your work. It is a last chance, not a first resort. The quicksave button is there for a reason. Please be sure to save your work under a series of different files to minimize lost work.
Otherwise, if you’d like to make a feature request, you can do that at Pixologic Support, tied to the email your license is registered with.
Take Care 
Not all files… didn’t work on an older .zpr file.