I found two papers related to my current research (A published in 2021, and B published in 2023). More precisely, all authors of paper A & paper B are from the same institute. Actually, one person appears in the author list of both paper A and paper B, so I assume that all the authors of paper B are (supposed to be) aware of the presence paper A.
However, I checked the reference list of paper B (the one published later) and didn't find paper A there. Actually, some of the key ideas of paper B are based on paper A, and I would say the authors of paper B must cite paper A to provide the readers a full understanding of the research background. I cannot really understand why the authors of paper B "forgot" to mention paper A there. It happens sometimes that people didn't cite relevant work from other people due to unawareness, but how it could happen to the same person with only a two-year gap puzzles me a lot.
I would like to ask: Is there any benefit for researchers to "hide" their previous research on purpose in any cases?
Background: I published another paper with some overlap with paper A without being aware of its presence between the publication date of paper A and paper B. I also forgot to cite paper A in my own paper.