That is not extraordinary. The bush's natural rose is the cherry colored one. The pink is trying to revert to its natural color. I have seen this in others' roses, not mine. I only have the cherry color, but this happens. The pink is a "sport." It is not unusual for a "sport" to return to its mother.

The parti-colored look is interesting. It may be that the stem bearing this rose will produce more like that, so you might want to mark it and preserve it. If it is stable, you can try to propagate it.

Cool bloom! :)

As mentioned, Blushing Knock Out (and Pink Knock Out) is a mutation, or "sport", of the original Knock Out. Known to do this from time to time. I currently have one cane with blooms mixed light pink and cherry red, and this year, one cane that is solid cherry red. Fun to see!

It's charming and I hope it will happen again from time to time for you!