It is some time ago now, but I want to mention that the ECMAScript Specification already defined the words "public", "protected", and "private" as reserved words in strict mode since ES 5 (ES 5 Future Reserved Words) and they are reserved words even in the draft of ES2022 (Keywords and Reserved Words). Therefore, I have a little hope that these reserved words will play a role in a future version of ECMAScript. Maybe the semantics of these words will be completely differnt from that of the meaning in other languages such as Java, but I think that it would be unlikely.
I used another syntax for protected in my suggestion here, but I wanted only to use a syntax that is as closely to the syntax of private as possible. Of course, I would prefer to use the keywords "public", "protected", and "private" if possible.