I am currently trying to migrate to Clickup - trying being the operative word, because it is so clunky to navigate around and try to add/edit new tasks. It would be really helpful to be able to edit the tasks 'inline' and/or have the task details open as a 'sidebar' rather than opening an entire new window (so when you click on the task, instead of opening the task as a whole new window, it splits the screen and you can see the details of the task on the side). Asana has a similar setup to this and people are familiar with it. You could still have an window option for those who like it (perhaps a double click opens the window?). Same for subtasks, when you are editing the subtask, it could open the details for that subtask in the area currently used for the activity (instead of having to open again, another window, and you are presumably not looking at the activity when you are editing the subtask anyways) - this being for window view - if a 'side' view is possible, you could just expand the subtasks, and then clicking on each of those would still show the details for that subtask on the side. It doesn't help that the windows are so slow to open either.
Some other annoyances: moving tasks (between spaces) needs to be way easier, currently you have to click to select the task, then go to the top, then select to move it, then navigate through to the space/project/list/etc that you want to move it to. That's about 6 'clicks' to do something that should be one. If you want to make something into a subtask, you need to go through a similar scenario (even if it is directly below the one you want to be the parent). There really needs to be a drag/drop scenario (or even if its on the ... menu), both for dragging a task to another space, and for dragging a task onto another one to make a subtask (or alternatively/in addition to, perhaps a quick indent button at the front of a task).