The table is correct. However, the table you pointed to earlier doesn’t address SonarQube Server at all. However, you can upgrade from any point release to any point release, so 2025.1.x → 2026.1.y works.
Why would you want to update to 26.1? it’s recommended to stay on latest community build release. If you are on 25.10.0.x you should update to currently latest 26.3.0.x with intermediate 25.12.0.x or 26.1.0.x (both are acceptable due to a bug on particular DBs in 25.12.0.x).
Indeed our table and calculator are not consistent here, but we decided to keep it that way to not complicate calculator.
I’d go with the upgrade path documented for the specific SonarQube versions you’re running rather than relying on the calculator alone. If the table and calculator are showing different paths, it’s worth checking the release-specific upgrade notes as well, since version requirements can change between releases. The calculator may be applying additional upgrade rules that aren’t obvious from the example.