I’m surprised no one mentioned the fact that the tires were brand new, and the whole different set of issues you have to deal with which go way beyond just making sure the tires clean.
The foam can be white as possible, but that’s not even the main problem you’re usually dealing with when it comes to brand new tires, the real problem is that brand new coating that seems to leach out of some brand new tires for sometimes up to a month. Sometimes it can be aggressively scrubbed clean and sometimes it just happens naturally and takes that month or so.
Looking at that tire it seems like that’s the case. Only thing that could’ve helped would’ve been nuclear prep, way beyond just 2-3 hand scrubbings looking for white foam.