D&D 5E (2024) Assassination on a PC yay or nay?

[aco175]

So at lvl 4 the PCs foiled the plans of a Shade. They watched her via a communication device dispatch an assassin and dark justicier to deal with them.

From a player perspective it seems that they did not know what was going on and if might feel cheap. The party foiled plans of the bad guys and seem to not know they were being spied upon and then punished by having a sneak attack in the middle of the night. I guess they know now that they can be spied on and that there are assassins being sent against them. They had no clue, then it just feels meh.

Maybe they could have learned they were being spied on or heard that someone hired assassins, they would have more options. The players might not even know who sent these assassins if there was no clues about a bad guy escaping and they were just being spied on somehow.

Going foreword, maybe he dropped something with a clue on who sent him or where he is from and what guild he is with. If the players have nothing, they have nothing to use or expand upon to make decisions.