Depends on the network coverage in your area I’d say. I for one have been using 5G (in France - excellent coverage) since I got my FP4 (in 2022), and never had any battery issues. Even when roaming in the countryside in countries with lesser 5G coverage (like Germany). It’s a typical case of “your mileage may vary”.
(5G is indeed more prone to attenuation by walls and such, but as I said, I didn’t notice. My phone gracefully switches to 4G when 5G isn’t available.)