I have had the unit for almost 3 years and have not experienced such a problem. In the meantime, some liquid is missing, but that is normal with all CECs, even if Arctic claims otherwise.

According to the manufacturer, the problem existed between May 2021 and March 2022 (see https://www.arctic.de/lf-service...). Newer units can be recognised by a small "QC Passed" sticker on the radiator. My cooler (purchase date 30.11.2022) has this sticker - I assume that new purchases are no longer affected and Digitec no longer has any affected units in stock.

I have never heard of a problem with leaking liquid. However, Arctic announced 3 or 4 months ago that a series of the Arctic Liquid II Cooler 280+360 had problems with the seal in the CPU cooling unit. The cause was a faulty vulcanisation of the seal.
(see. https://www.youtube.com/watch)

Whether an AIO is affected can be determined via the Arctic website (see: https://www.arctic.de/lf-service...). Only units produced between May 2021 and March 2022 are affected.

I have such an affected unit in my system and that is why I contacted Arctic. About 4 weeks later Arctic sent me exactly the service kit that is presented in the Youtube article by Gamers Nexus. On a Saturday afternoon, I bit the bullet and exchanged the seal. It took about 1 hour and was unproblematic.