A very short post.
The discussion on page 9 of the referred paper starts with:
"Our findings provide evidence of the spike protein hijacking the DNA damage repair machinery and adaptive immune machinery in vitro. We propose a potential mechanism by which spike proteins may impair adaptive immunity by inhibiting DNA damage repair."
Please indulge me and allow me to explain the difference between science and mathematics.
In mathematics a conjecture (a bit like a hypothesis) can become a theorem; theorems are proofs and are generally unassailable (unless you are Fermat 🧐).
Whereas in science, there are no theorems (unless you are referring to mathematics); just hypotheses that become more and more accepted the more that they are independently repeated and arrive at the same or similar conclusion. Fine tuned obviously, but never proven; just pretty damned close to ideal.
And that's how vaccine development goes.
The paper refers to this process; it finishes with:
"This work will improve the understanding of COVID–19 pathogenesis and provide new strategies for designing more efficient and safer vaccines."
This Doctor explains what's going on much better than I could.