Not sure if I used the correct terms but what is the difference in security and privacy between downloading from a public wifi (or a closed wifi; with password) and mobile hotspot (sharing 4G/5G data from your phone to your computer)? Which one is recommended or does it not matter?
It depends on his threat model and what he’s trying to hide really. Public WiFi is fine, as long as you validate/check the SSL cert it’s using is from your bank and is legitimate. Using public WiFi with a VPN is more secure as long as you trust your VPN provider. If he’s asking these questions, then he’s probably not doing banking though, and should ideally be using VPN+TOR or something similar.