Hi Viion,

The Japanese post looks like the same thing.
[dev1206] プロテス／シェルの効果が同時にかからなくなり、あとからかけた効果が上書きされるようになります。

The only things I can think of is the Ironwill Unguent item that provides a powerful Shell effect. And that Shell for players (perhaps different effects in the future) could be reintroduced in the future.