30*
And they did mention on their Twitter (X) that PL will get 30 save slots just like PK. The save you lost is probably just somewhere in the save files folder.
I’m not on my PC so I can’t exactly find it, but if you’re on Windows, then press Windows+R and type in %appdata% or %localappdata% (I’m not sure which one) And search for Paper Lily or Leef6010, in which should be a folder named saves. Note that PK saves are in the same folder as PL.
Btw PL means Paper Lily and PK means Project Kat