The device zone rules, guide timestamps or an old manual offset may not agree after a daylight-saving change.
Why this happens
A guide that is consistently one hour out after a clock change deserves a different investigation from a channel with no schedule at all. The video can keep playing normally while the displayed programme times are converted using an outdated rule or an extra manual shift. Some viewers add an offset during one part of the year and forget it later. That can make an otherwise correct schedule look wrong when seasonal time changes occur.
Start with automatic device time and the correct location-based time zone, then review any manual guide offset you previously added. IANA notes that time-zone rules can change through political decisions and reach users through software updates; a fixed UTC offset is not a complete replacement for those rules. Do not change every programme individually to compensate for a consistent system-wide shift. Compare one live programme with its guide row and keep the before/after values so an unsuccessful adjustment can be undone. If only one channel remains wrong, treat its mapping or source data separately.
A useful way to work through it
Verify the device’s location-based time zone and normal automatic time setting.
Record and review any existing manual EPG offset.
Compare a live programme before and after one reversible correction.