My info is several years out of date so take with a grain of salt. Pix is a phenomenal in country payment system. One of a couple of the best next gen payment rails.
But its design is very much hard to work with for international transactions. It has some risk rules and design choices that make this true. I believe this is intentional as Brazil wants to maintain pretty conservative currency controls.
But! Similar things could have been said about pix and online shopping rails. It wasn’t great for that as it wasn’t the primary use case. And that is changing fast so maybe the international use case will improve.
UPI in India for instance does international work well in a similar conservative currency environment.