Slug based folder structure when not using title field

Description

I am having an issue with the folder structure in assets in certain scenarios. For certain projects I quite often set the default asset upload location as the {slug} of the the entry to make it a little bit more manageable. I am having an issue on a site currently where I am not using the title field and instead using custom 'firstName' and 'lastName' fields. When I create a new entry and haven't yet saved the entry, any uploaded assets seem to generate a temp folder and get uploaded there instead of under the slug. This is only an issue when not using the title field.

Steps to reproduce

1. Create a section which uses alternative plain text fields instead of title field
2. Add an asset field which uses the {slug} as the default folder structure
3. Create a new entry
4. Before saving the new entry add an image to the asset field

Additional info

• Craft version: Craft Pro 4.5.6.1
• PHP version: 8.1.21
• Database driver & version: MySQL 8.0.33
• Plugins & versions:

Reproduce this in Craft Pro 4.5.6.1 by creating a section with custom firstName and lastName fields, configuring an asset field with a {slug} folder structure, and uploading an image before saving. Done means the unsaved entry's asset is placed in the intended slug-based folder rather than a temporary folder; compare behavior with a section that uses the title field.