Notes about upgrading to FreeBSD 15.0
Use FreeBSD Update to upgrade to 15.0. At some point before 16.0 you should pkgbasify but there's no rush since FreeBSD Update will be supported for the lifetime of 15.x.
Using pkgbase on 14.3 has always been considered "experimental"; I'm glad people tried it out and found some of the bugs in pkgbase early, but it's not the path I would recommend to users.