When Monarch: Legacy of Monsters Season 1 began, it did feel like a bit of fridging occurred. That came when Keiko Miura was seemingly eaten by an Endoswarmer nest as they pulled her down into a Hollow Earth crevice in Kazakhstan. A few of the nine episodes did feature Keiko in flashbacks, but it did feel off that the brains behind the Monarch project wouldn't be there in the future.
Source:https://www.cbr.com/monarch-legacy-of-monsters-keiko-miura-return/