Assassination missions difficulty creep

When taking on assassination missions repeatedly in the same place the NPCs slowly start getting buffs until they go from solo pythons under fire from local system security and die fairly quickly to overcharged, 4-wing, 20+ chaff-spamming (i counted) fer-de-lances, with some more noticeable differences being:
1) absent security on arrival as well as no response timer
2) their shields having more effective HP than a engineered corvette with all 3g boosters
3) lasers that penetrate shields (no railguns)
It is clearly intended, but the payout and target threat of missions doesnt change so its just annoying to deal with.