Do you hear a chime before it pops up? Maybe the "talk to assistant" gesture is being invoked accidentally/unintentionally: https://support.google.com/assistant/answer/7513985?visit_id=638282594601460963-2105321338&rd=1#zippy=

I use Chrome on Android and it continues to run into invalid csrf token even when the cache is cleared. This usually resolves itself in a few days.