SUMMARY When Discover shows an "Updates available" icon in the systray, it has a hover text that updates are available, but the text does not contain the number of updates. It should probably be easy to include the number, maybe even split into security updates and normal updates.
It used to be like this, but the number is meaningless. You can have big apps in 1 update and tiny ones that are 23. Just a small Plasma update will be tens of updates on many distros. I don't see how that would inform anyone about whether to update their system.
I'm inclined to agree with Aleix. The number does have *some* meaning; an update with 2 things is likely to be smaller than one with 8,000 things (as I often had on openSUSE with LaTeX packages installed), but ultimately the number doesn't really help you make any decision or change a decision you would make, so I agree that it's not useful to add.
You also can see "It were 12 updates in the last few days and now it are 112" Beside, if one has the number it shouldn't hurt to put it there. The tooltip feels incomplete without the number.