Did you upgrade your "Google Home Premium" subscription for your cameras (formerly Nest Aware)? I don't think the subscription level should affect the language.
However, if you signed up for early access to "Gemini", I found this statement on this Google Nest blog: https://www.googlenestcommunity.com/t5/Blog/Welcome-to-Gemini-for-Home-voice-assistant-early-access-...
"Language support limited to US English during early access. We are working to add other language support in early 2026. Currently US English is the only supported language and your devices will switch to this if you upgrade to the Gemini for Home voice assistant on your speakers and displays."
Judging from other posts in this forum, I do not think you can uninstall "Gemini" once you've enrolled in it.
(I'm just another Google Nest customer.)
