The Nokia 9 PureView was plagued by several launch delays that saw it finally released earlier this year, with an outdated SoC. Its successor, the Nokia 9.1 PureView, has apparently been hit with a similar delay.
https://www.notebookcheck.net/Nokia-9-1-PureView-reportedly-delayed-could-be-DOA.440320.0.html
They need that ISP to be relatively independent from the SoC, or else they'll never catch up.