Honestly, I think slight graying out is fine, but currently, it's just too much. Especially when it comes to lower levels when you keep indenting the list, the greyed out text becomes very difficult to read, e.g.
I voted no. Yes, the task is completed/checked off, but it's still part of my note. Graying it out makes the note more difficult to read (light grey on white).
I used to run status meetings with checkbox for to-do items. At the next meeting, I want to review what was completed. Constantly trying to read grey-on-white just gave me a headache, and I ditched the checkbox.
It's not asked, but I have the same problem with to-do notes. There's an option to show or not show completed to-dos, or I can delete them outright. Letting users keep them and visible, but difficult to read, is again headache inducing.
I'm using Microsoft To Do application for to do lists. It's graying out, crossing out, but also hiding ticked items. It works great like this. But Joplin is not a todo app so I'm not sure if it would work the same here. Still, in my opinion, graying out plus crossing out items might be the best.
I like that the item is grey-out and voted to keep it. However the poll shows I'm in the minority. If you must change it, I propose that it be user selectable, Maybe ever with a color wheel or a grayscale slider for further customization.
To make it clearer the text is grayed out and made harder to see? Maybe it's just my ancient eyes but grayed out text appears less clear to me. This is a half-full vs. half-empty type thing. I'd prefer to see bright things that have been completed and the sordid tasks yet to be done grayed out. Less of a reminder that there's still that nasty stuff called "work" (pardon my language) to do.
I appreciate visually that it's grayed out, easier to read the note.
But I still voted no, for overall UX best practices. To me grayed out means disabled / not editable. It gets confusing to use it for enabled but "done" things.
But I don't care all that too much, whatever fine people most useful is fine.
Personally I (with much assistance from this forum) have tweaked my .css to also strike-through the text of completed tasks, which remains my favorite.
So I can do without the grey, but if the greying out is changed, perhaps the strike-through option can be added?
After some consideration I've voted Yes (checked checkbox should be greyed out).
I understand that the alternative is no visual indication (other than the tick in the box and blue color of the box) that it's checked out?
I also think that people might not know what they are voting for. They know how it looks now, but they can only imagine how it would be. They might regret the change after it's done.
PS. I'm using stock editor on Android and PC. I wonder if people voting NO are using it as well, or the other editor which seems to have severe issues...