Preview has deleted all my signatures, won't let me save new ones!

Perhaps an aspect in the Apple Support document will assist >>

link below

Fill out and sign a PDF form in Preview on Mac - Apple Support (CA)

Excerpt from above link

• Create a signature using your computer’s built-in camera: Click Camera. Hold your signature (on white paper) facing the camera so that your signature is level with the blue line in the window. When your signature appears in the window, click Done. If you don’t like the results, click Clear, then try again.
• Create a signature using your iPhone or iPad: Click Select Device to choose a device (if more than one is available). On your device, use your finger or Apple Pencil (on iPad) to sign your name, then tap Done. If you don’t like the results, tap Clear, then try agai

As promised and have just successfully created an new Signature

This was created on a M2 MBA with Ventura and using the Preview Application

With a hand printed P. Phillips ( not real signature lol ) used the Builtin Camera

Method was Create Signature and Tab at Next Camera and presto and viola Signature

Refer to below

Will have to experiment when I get on the M2 MBA with Ventura 13.2

only to compare sometime in High Sierra macIS 10.13 used the built in camera in old iMac to create a really signature

Have gone through maybe 10 -12 new machine since then

The same signature had followed me around on every machine up to and including Venture on two M-class computers

will try and get back to you