What was reported at the time
TheWrap reported on July 19, 2021 that House of the Dragon's UK production had paused following a positive COVID-19 test. Its account described a two-day interruption with work expected to resume that Wednesday. Those were the plans and circumstances reported then, rather than a new pause affecting today's production schedule.
Source [1]Filming, broadcast and cancellation are different stages
A temporary stop to work on a set does not automatically mean a series has been canceled or that its premiere has already been delayed. A broadcast date requires its own announcement, and a production restart requires evidence beyond the original plan.
The story concerned a Game of Thrones prequel, not a resumed season of the original show. Keeping the title and production year explicit prevents unrelated updates from being combined. The Witcher guide provides a separate example of a continuing fantasy series changing its lead performer without starting its whole narrative again.
Source [1]