There isn't enough meat here to say if this is expected or nefarious. For one thing those in FL over 90 yrs are a few percentage more registered D than R. So voters removed from rolls due to SSA dB death records or FL death records will favor D over R by 5%
We don't know how many are students, which are the largest group of purged through postcard address verification. Moving states, registering in other counties, not updating address, etc. Younger FL voters are more likely registered D than R.
You'd want to look at AAMVA and ERIC lookups, and where the purges come from. You are also removed from voter rolls for not voting in recent federal general elections (last two)
On the other hand, Florida Republicans have actively improperly ratfucked the rolls like 2000.