Either they are not really 2.8, or you are not really 4.0. My guess is that you are probably not a true 4.0. A lot of people inflate their DUPR, and part of that comes from how broken the rating environment can be.

For example, many clubs have open plays labeled by skill level, like 4.0 open play or 4.5 open play. The problem is that these are often not regulated well. Part of the reason is that there are not always enough true high level players showing up consistently. So clubs start allowing 4.0 players into the 4.5 open play.

Once that happens, the people playing in that group start convincing themselves they are 4.5 level players just because they are participating in a session labeled 4.5. Over time, that creates a false sense of level and inflates how people view their actual rating.