Google Assistant is all over the place :-P
I also use weather… and yesterday the assistant told me I would need to unlock my device to do it, but then also just showed me the weather.
Google home is getting more unless by the day, think it's all tied together.
As more and more services get added to Android in general, I think we all are going to have to get much more specific with our commands. "What's the weather for today (or this week)" probably will get the job done.
The thing is, GA on Android TV is one of many google apps without changelog when an update is published, let's take another one like Android Auto, there is no foreseeable future when voice commands will work properly
Works fine for me from the home screen. Were you in the YouTube app?
You might want to try uninstalling the “Google” (search) app from the system apps list. I’ve had a bunch of similar faults with the latest version. See my post regarding volume change requests returning a search result, similar to this. It’s really garbage that this is so unreliable and clearly not been well tested. You’ll also need to disable auto updates.
Hope this helps.