“You” is also a polite plural that became default and displaced “thou”. Probably slightly differently but in the same category.

https://www.merriam-webster.com/words-at-play/why-did-we-sto...

The pronoun that had previously been restricted to addressing more than one person (ye or you) started to see service as a singular pronoun. Initially you was used to refer to a person of high social standing (such as royalty, who would be addressed as “your majesty”) but soon came to be used as well when speaking with a social equal.

As a result, poor thou was downgraded, and was used primarily when referring to a person of lower social standing, such as a servant. However, this pronoun did not disappear, as it also functioned as an indicator of familiarity or intimacy, and retained its function as a singular form of address for God in many cases in ecclesiastical writings.