Not all Upwork functions and features are available on the mobile site as of now, so we recommend reserving critical site functions for your desktop rather than mobile device. The main reason we don't support it at this point is due to concerns about the quality of the applications that might result through a mobile device, but the product team is considering it for the future.
I have no idea what you mean by "it," nor for that matter by "critical site functions."
The OP seems to have a (vaguely stated) issue with notifications. Surely notification is a core function of any mobile app, and should be already robustly implemented, not under consideration.
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