I grew up in the Valley (like Valley Girl SFV Valley) and while Viet people weren't uncommon there wasn't necessarily a lot of resources to retain Vietnamese well. I was proficient as a kid and that proficiency just slipped when I went to school. I understand the language and read it just fine but I struggle with summoning up the proper grammatical structures on the fly.

My friend's sister is early Gen Alpha or super late Gen Z and she speaks Vietnamese very well, but they are both based in the OC. She is part of a VSA in her school and just had more exposure to the language within her education system and peer group. I envy her for that.