Some code completion suggestions are helpful in #PositronIDE, but the writing suggestions in Quarto and markdown files get me crazy. Finally discovered how to turn them off!
In Settings (gear icon at bottom left), turn off the "Editor > Inline Suggest" and "Inlay Hints" settings. You can do it just for certain file types, like @lang:quarto, @lang:plaintext and @lang:markdown - search and then disable in the correct workspace.