There is no longer any warnings when you are about to enter minor victory systems. If you have neutral standings and enter a triglavian minor victory system you will be killed by the camping triglavians.
This same happens with all EDENCOM systems including minor victories and fortresses so if you have any negative standing to EDENCOM then they will shot at you!
Only way to know what systems are invaded is to use the ingame map (F10) and set your NPC activity setting to -> show triglavian minor victories, edencom minor victories or forts. There are NO TRIANGLES on your autopilot route either so you can’t trust that either.
The only way to avoid these systems while traveling IN HIGH SEC SPACE is to open your autopilot settings and to put it to avoid these systems. If you manual pilot in high sec space (not following the yellow gates while this setting is on) and you do not know what systems are invaded you are very likely going to get killed!