It has the same issue, and if you boil down that formula by removing piece by piece, you will find $\sum_{k＝1}$ still cannot render, it seems mathJax v3 does not handle some unicode because the equal sign here is not ASCII code.
@MartinSleziak I have checked Approach0 parser, it does not digest Unicode equal sign in particular. So it is expected the results are different, because it simply ignores unrecognized token(s) and in this case the k=1 becomes k1 which is converted into multiplication semantic tree.
