Citation manipulation is a violation of best practice, and authors submitting manuscripts to MDPI are expected to include only relevant citations, as per our Citation Policies. MDPI journals do not engage in citation manipulation.

An internal investigation brought the following results:

• We have identified a total of 47 articles across these four journals that potentially contain an excessive number of "journal citations" linked to a journal published by a third-party publisher.
• In accordance with our complaints policy, we have contacted the authors to comment on the situation and provide detailed justification for the significance and relevance of each flagged citation within their respective articles.
• Our editorial board is actively engaged in this matter and will thoroughly review the comments provided by the authors. Subsequently, we will determine if amendments to the scientific record are necessary, in accordance with our Update to Published Papers policy (available at https://www.mdpi.com/ethics#_bookmark30).
• Should it be deemed necessary, we will collaborate with academic institutions to address the behavior of the involved authors.
• Furthermore, we are in the process of updating our internal procedures to prevent similar situations from occurring in the future.

Five of seven MDPI journals included in the 2021 list have since been removed, as have the three MDPI journals included in the 2023 list, reflecting MDPI's commitment to collaboration and adherence to best practices. The previously listed journals had been included solely due to their high publication growth numbers.

We remain committed to addressing the concerns raised by CAS. We believe that the investigation into the alleged citation manipulation will result in the removal of our journals from the Warning List.