2 things...
Number one:
this is not all that uncommon. Especially for members if a party whose candidate is an incumbent for whom they need not vote. Rush Limbaugh asked his audience to do that in a couple of elections, calling it, "Operation Chaos."
Upstate Representative files "Closed Primary" legislation in Columbia.
www.audacy.com
And in 2020, with Trump being the incumbent, that was the perfect time for Republicans to do exactly that in states like Florida which have closed primaries.
Number two:
Whoever created the maps in the OP intentionally picked March, 2020 as the starting date of their claims. That was the month of the Florida Democratic primaries which would have the most Republicans registered as Democrats. The maker of those maps clearly intended to show a switch from blue to red which doesn't actually exist. Most Florida presidential elections have been fairly close for many years now. I don't see a reason for that to change.