Let me elaborate.
Science when investigating the causal relationships of physical phenomena would certainly be totally compatible and fits nicely with physicalism philosophy. And due to many scientific fields limiting their field of study to the causal relationships between physical phenomenon, it’s natural to use the thinking of physicalism to do science.
However, the philosophy of physicalism is that there’s only physical things, mind is a software to the hardware of the brain, and not fundamentally having it’s own laws other than the physical and emergent properties. The complexity of mind matter interaction that produces rebirth in dependent origination 3 lifetimes model is unable to be covered by physicalism philosophy for it implies that the software, the mind can survive somehow the hardware being destroyed (brain dead) without an explicitly physical connection to the next brain/body to have the continuity of software.
Scientism limits the world to physicalism alone and would view things from the lens of physicalism, if anything cannot fit in, it is rejected. Rebirth is rejected apriori from the range of possible things that nature can do because the fundamental philosophical choice of naturalism, that is to assume nature obeys physicalism philosophy.
It’s only natural when investigating the causal relationship between physical phenomenon to find that scientific findings support physicalism, but that’s different from claiming that nature can only behave according to physicalism. Science cannot prove physicalism philosophy to be true, no matter whatever discovery they make within the causal relationships of physical realm. Thus this makes it that physicalism is a philosophical choice, not a fundamental part of science. More like a paradigm. Physicalism can be falsified by just one rebirth evidence. Of course in practise, it takes a lot to overthrow a paradigm.
The mind with Jhāna, supernormal abilities can discern a lot of things including past lives, divine eye can see gods, Brahmas, mind can read minds, etc. Basically unless science adopts these supernormal sensory powers as tools of investigation, it is not able to investigate the range of phenomena that is included in Buddhism, including kamma, rebirth etc.
I also like to use the analogy of the Catholic church towards Galelio. Instead of updating current views based on evidences (the scientific method), they choose to double down on earth centred cosmos, due to theological philosophy. Viewing the world via the lens of philosophy instead of data. Now it’s physicalism suppressing rebirth evidences.
It’s one rebirth model, a little bit similar, we would say that their model is flawed for they don’t see it long enough to discern that heaven and hell too are impermanent and there’s further rebirth down the line until one attains to arahanthood.