Purification of mixed index funds or EFTs

Salam,
I am recently had to invest in one of the mixed index funds (like FXAIX) in my retirement account. I was looking to purify my gains but i didn’t find what i need in Zoya.

Taking FXAIX as an example,
It said in the AAOFI report in the app, that non-compliant funds are 24%. is that means that purification percentage is 24% of the capital gains (using AAOFI method) ?

Int eh step-by-step guide, it mentioned that the report will mention non-compliant capital gain, but i didn’t find similar information in index funds / ETF (and it is extremely difficult to check each of the 500 stock option in the fund).

Can you help with that ? How to purify index funds (not regular stocks) ?

JAK
Ahmed