According to https://eel.is/c++draft/over.literal
double operator""_Bq(long double); OK: does not use the reserved identifier _Bq ([lex.name])
double operator"" _Bq(long double); ill-formed, no diagnostic required: uses the reserved identifier _Bq ([lex.name])
Obey that rule by keeping track of the operator literal name status wrt. leading whitespace.
This is per-declaration state; I don't think we can reasonably store it on IdentifierInfo, which is global information about an identifier. This will do the wrong thing if (for example) literal operators with the same suffix but different whitespace are declared in different scopes or if the same operator is multiply declared with different whitespace in the same scope.