Challenge of the week hitting stats changed

[LookatTheRhino_PSN]

For challenge of the week, I just did a few rounds where ketel martes stats were
109 con L
110 pow L
73 vision

Now I restarted another round and his stats are
99 con L
99 pow R
73 vision

Does this always change for cotw? Found it weird to have his stats drop from one round to another

[LookatTheRhino_PSN]

Restarted again and his stats went back to the first set