I think im going to try this 1
https://nl.aliexpress.com/item/High...75d54be&transAbTest=ae803_1&priceBeautifyAB=0
It says it as 3800 mah i doubt it but can always try
I already tried an "official" battery from aliexpress but it caused my phone to crash once in a while and didnt startup until i put the charging cable in
Just got off support from oneplus they give me their we dont sell spare parts sorry answer

However they told me it would cost around 30-35 euro to put in a new official battery this isnt much but i dont like sendign my device away the last time it took only 5 days but still.
Why cant we just buy spare parts