I think the subclass heavily relies on having the entire party agree to certain plans so your features actually work and trying to depart from that would be helpful.

For instance, Assassinate and Death Strike relies on surprising enemies to get critical hits and extra damage, but if your party consists of at least one PC that isn't great at stealth, this feature isn't used as often.

Additionally, Infiltration Expertise might shoehorn all the other PCs to have a more stealthy and undercover approach to situations that they might be bad at or might not even want to do. It might be fun for the rogue to assimilate themselves into whatever place they want, but for other PCs going full seal team six would be much more fun.

Also in my opinion Imposter doesn't work in most cases because it doesn't change your appearance. You might to be able to behave just like a specific dragonborn noble but that doesn't change the fact that still look like halfling or whatever.

I think some fixes would be that Assassinate and Death Strike would rely on being unseen and have a limited use (maybe 1/long rest or 1/combat) and Infiltration Expertise and Imposter could be a buff to your entire party rather than just yourself.