First off, the new espionage system is a complete redesign (motivated by widespread discontent with the previous system, discussions on how to rework espionage had been going on for a long time). Because of the scale of the rework, I wouldn’t expect another major rework in the near future and so I’d like to encourage everyone to familiarize oneself with how the new system works. The proposal describing the system can be found here (
https://forums.civfanatics.com/threads/6-cp-espionage-system-overhaul.685902/), with some minor modifications as described here (
https://forums.civfanatics.com/threads/6-cp-tweaked-version-of-azum4rolls-espionage-overhaul.686239/).
As others have already noted, it is not correct that there‘s no way to protect oneself against enemy spies. A counterspy can be used to significantly slow down the progress foreign spies make. Example: If a rank 2 spy is used against a civ that‘s 5 techs ahead, the spy will generate 40 NP per turn (20 base, 10 from spy rank, 10 from tech difference). If the city owner uses a rank 2 counterspy to build a counterespionage network, NP generation will be reduced by 20, so the attacking spy will need twice as long to complete a mission. This is comparable to the missions having a 50% failure chance.
In addition to using counterspies, it’s also possible to increase city security to slow down foreign spies.
AI tends to steal Great Works most of the time, because it's the cheapest action now.
That‘s not correct, the AI choose missions based mostly on strategical/tactical considerations, if they‘re behind in tech they prefer to steal technologies, if they want to go for a CV they prefer to steal Great Works, etc. Other factors like their relationship to the owner of the city also play a role in deciding which city/mission to choose.
Also stealing GW will take random players' GW, it's not even related to those being in the city spy operates in.
That‘s also not correct.
The new system assumes a human player isn’t too far out ahead that every other player is sending all their spies to them, but that’s precisely what happens in lower difficulties. Some people don’t like playing from behind, and the modders failed to respect that with this new system.
They did not. Quoting from the proposal:
"Add the following Security modifiers:
Settler difficulty: +20
Chieftain difficulty: +10
Players on lower difficulty levels will likely be targeted by spies more often due to being in the lead, and players still learning the game should get a buff to their Security as a result."
If necessary, those modifiers can be increased or given also on mid-level difficulties.
On a general note, providing feedback is always appreciated (as the new system is a very large rework, it‘s very likely that adjustments will be necessary), but please familiarize yourselves with how the new system works before doing so. Also, it‘s best if feedback is based on actual experiences made while playing and not on assumptions or expectations.