Cannot disable spell check in several apps

Some apps like Asana, Todoist or others highlight English text with red lines. It concerns apps that can also be used via internet browser. Context menu reveals that this is a spell check (name of the spell checker app not provided). I have turned off ALL spell checking features of Windows 11 and of all my internet browsers. I do not have installed any spell checking software currently. I have deleted all program folders of former spell checkers like LanguageTool. I have looked into the installed apps, the running processes and the Windows services – no spell checking routine detected. A second laptop with Windows 11 does not show this wrong behaviour. I suppose that some apps are using a kind of spell checking API, but I am not sure. Does anyone meet the same problem? Do you know a good solution?

As explained in my post: I have already turned off all Windows autocorrect features in Settings. Same for registry (everything is zero, here). So, not yet solved.