English is extremely stingy with pronouns in general; beyond singular vs plural they, there's also no proper plural you, no modern informal you (it was 'thou', but that's archaic), no exclusive vs inclusive we, and so on.
Thank you for teaching me something - I did not know that this existed (https://en.wikipedia.org/wiki/Clusivity)
I don't know what y'all are talking about.
"You" can refer to either one person or multiple people.