FFVII Re undeperformance on PS4 is a fact, but to somewhat extend this underperformance to PS5 version sales is far too much
The pool of PS5 owners who owned PS4 might be closer to 100%. If you offer your whole library for free your only reason to rebuy games you already own is for collective purposes, which is absolutely the case here
So any PS5 game that is free delivered from PS4 isn't expected to sell at all, except for collectors or for the very small non-PS4 owners who have a PS5
All comparisons for non free delivered games are ultimely pointless, unless the system is fully BC. If you want a fairer comparison I think SMT Devil Survivor is the way to go
DS version sold 310k, 3DS version sold 4 years later sold 120k. Need to point however to play additional content you really needed to buy the 3DS version, for FF VII you can skip it and just buy the DLC
If some day Sony reveal the DLC sales numbers for 7RE and they are abysmally, then I would be worried, until there it's hard to be concerned with people choosing to not buying a game again after just 1 year
