kendo.timezones.js is generated from an outdated IANA tz database. The Canadian zones that moved to permanent standard time still observe DST in Kendo, so dates are off by one hour.

Reproduction

kendo.timezone.offset(new Date("2026-12-01T12:00:00Z"), "America/Vancouver");

Current: 480 for Vancouver, 420 for Edmonton, 360 for Winnipeg (DST rule Canada still applies).

Expected (tzdata 2026b-2026e, latest 2026f): 420 for Vancouver, 360 for Edmonton, 300 for Winnipeg. America/Inuvik is also affected (-06).