I have this complaint about the Software Store, as well.
This is a common complaint about ProtonVPN. ProtonVPN creates a new configuration file in Root that sets up your network to respond through the VPN. Well... if you remove the ProtonVPN, that configuration file gets left behind, without the VPN to route through and so the network stops working.
This is a Major Annoyance for the user. The remedy is to deal with that configuration file. It is simple to solve - as long as you magically know about it.
This forum is here and you can check ahead if you have any doubts and use it as a resource as often as you need.