SHA256 (2.5.tar.gz) = U588MSowla/BF64sMRFjD5dKHJnd57C3vr8W7nqGKgc=

Not OK.

All of these lines...

V=              2.5
DISTNAME=       ${V}
PKGNAME=        stellarsolver-${V}
WRKDIST=        ${WRKDIR}/stellarsolver-${V}
HOMEPAGE=       https://github.com/rlancaste/stellarsolver
SITES=          https://github.com/rlancaste/stellarsolver/archive/refs/tags/

...should be replaced with

GH_ACCOUNT=	rlancaste
GH_PROJECT=	stellarsolver
GH_TAGNAME=	2.5

or the DIST_TUPLE alternative.