My first mixing experience was with
https://tumbler.io and they asked me to save my mixing code which I did,
Personally, I do not like the idea of mixing code. It is true that you must trust the mixer and that all the mixers currently in place are centralized, but using that code may mean collecting more data about you or that they do not delete the data as a worst-case scenario.
@OP should change the title to "Warning, Uphold is refuse funds from mixer".
I don't think he would do that, and he didn't even try hard to defend his arguments.