If in 2025 your unscrewed battery is disconnecting evening at vigorous shakes it is not your fault at all. So that doesn't explain the "bring in the screws".
There must be something to tighten the contact between the phone and the battery, every other manufacturer uses glue, Fairphone tried to solve this problem with plastic clips before and it wasn't reliable enough, so I'm certainly not gonna blame them for doing it with the most effective method that doesn't compromise repairability.
So I'd consider screws to be an improvement actually.