You are absolutely right. In the dialect of colloquial American English that I grew up speaking, bare “you” can only be singular, and the default plural 2nd per

You are absolutely right. In the dialect of colloquial American English that I grew up speaking, bare “you” can only be singular, and the default plural 2nd person pronoun is “you guys”. Telling us not to use it because of long-forgotten etymology would be as absurd as telling us not to use the word “they” because it’s a product of Norse imperialism.