For info,

Following an update, my DeepL plug-in for Studio 2022 recently stopped working and would not recognise my API key.

The problem was that Studio was not removing the old plug-in when trying to uninstall within Studio.

The DeepL plugin needs to be removed using the Plugin Installer directly.

The path to the Plugin Installer on my computer is the following: C:\Program Files (x86)\Trados\Plugin installer. You double click on the .exe file to open the window to uninstall your plugins. Then just reopen studio and reinstall the latest version of the Plugin.

Hope this is helpful for anyone with the same issue.