While i was reading the spec(ECMAScript 2022) i've wondered which nonterminal symbol is the start symbol ? in other words the first place that is being evaluated in ECMAScript 2022
It depends. The abstract operation ParseText is called from 14 places, with different goalSymbols (from the perspective of a bottom-up parser the start symbol of the generative grammar is the goal). The call you are probably looking for comes from ParseScript and passes in the Script non-terminal symbol (though it might also be Module passed in from ParseModule).