@taffclarke
Google Nest seems to rely on a Google database (perhaps from Google Maps?) that specifies a timezone for each address in the world. That database has errors in it. Google Nest seems to have no process for correcting such errors in its database. In fact, some Google Nest Support people act as if there is no such database, and keep telling the customer to factory reset their device, and the problem does not get resolved.
Two years ago, a customer in Queensland Australia reported a problem similar to yours. After numerous exchanges with Google Nest Support, Google Nest locked the thread without any resolution (the flagged "answer" was from another customer and did NOT address the problem in Queensland):
https://www.googlenestcommunity.com/t5/Speakers-and-Displays/Time-Zone-incorrect-on-Nest-Hub/m-p/105...
Over the last couple of years, I've seen other posts from other customers in other parts of the world who also have erroneous time zone assignments, who also could not get Google Nest to address the issue. The only time I know of where they did address the issue was when much of Mexico discontinued daylight savings time, and even then it took them months to correct the problem. But even now, border towns in Mexico report they have incorrect times.
See these posts:
https://www.googlenestcommunity.com/t5/Speakers-and-Displays/Display-show-incorrect-time/m-p/607341
https://www.googlenestcommunity.com/t5/Speakers-and-Displays/Wrong-time-zone-MDT-Utah-Arizona/m-p/60...
https://www.googlenestcommunity.com/t5/Speakers-and-Displays/Wrong-time-zone-DST/m-p/607336
