Thank you for letting me know I'm running the latest version.
I ran the updatechecker and have the same results:
carl@pihole:~ $ sudo pihole updatechecker
carl@pihole:~ $ sudo pihole -v
Pi-hole version is v5.17.2 (Latest: v5.18.2)
web version is v5.21 (Latest: v5.21)
FTL version is v5.25.1 (Latest: v5.25.1)
carl@pihole:~ $