BottomNavigationBar has no API for enabling/disabling its tooltips. Widgets that implement and use tooltips must also include an API that can be used to set the tooltip string to a value that differs from its default tooltip string(s) and to completely disable its tooltips. BottomNavigationBar now always shows its icon label as a tooltip on Web and Desktop, which seldom adds any value to the often already shown icon label.

Then newer BottomNavigationBar that uses BottomNavigationBarItem that deprecates title in favor of label is currently not very desktop/web friendly when it comes to providing control over its tooltips. It misbehaves to the extent that it is an issue.

1. There is no way to turn of the tooltips!
2. There is no way to provide a tooltip label that differs from the icon label!

Q: What value does the additional tooltip label that is identical to the already shown icon label provide?

If there was a way to via the API e.g. as a new property in BottomNavigationBarItem to provide a separate tooltipLabel that could provide some additional info in addition to the already visible string in the icon label, then its tooltips might be made more useful.

For BottomNavigationBarItem it could e.g. be added so that it uses label for tooltips by default and a separate tooltipLabel value if one is provided. There still needs to be a way to turn of the tooltips as you might not want to have tooltips at all on desktop and web when using the widget.

Many web and desktop may want to implement a global user controllable feature that enables and disables tooltips in the app entirely. Tooltips are nice for beginners when you are not familiar with the app, but when you know the app they tend to get annoying and get in the way of using the app. Providing users a feature where you can turn off tooltips is a nice way to increase the UX for more experienced users of your app.
Currently many widget in Flutter that uses tooltips make it impossible (or at least more difficult than it needs to be) to implement this feature as they have no way of turning off tooltips at all. The BottomNavigationBar is one critical widget that fails in this respect.

This example with the bottom navigation bar is based on the API docs sample:
https://api.flutter.dev/flutter/material/BottomNavigationBar-class.html

Where the deprecated (in beta channel and higher) title was replaced with label. On web and desktop platforms this results in a bottom navigation bar where there always is a rather useless extra tooltip that is identical to the label, with no apparent way of turning it off in the API or changing the tooltip label to something else. The only way to fix this now seems to be to fork both BottomNavigationBarItem and BottomNavigationBar and make custom versions of them, which from a maintenance point of view is less than ideal.

Example BottomNavigationBar code snippet:
https://gist.github.com/rydmike/e97d29789886b9b406618d851d765fff

Can be tried in DartPad here:
https://dartpad.dev/e97d29789886b9b406618d851d765fff

Related issues

The BottomNavigationBarItem case is just one example case, there might be more Widgets with similar tooltip issues on web and desktop. One found related sister topic is the similar issue with PopupMenuButton #60418.

Background

This issue was previously included as the 2nd part of the new feature proposal "Global enable/disable of tooltips in Flutter apps and provide API control over widget tooltips" #66993. I removed this issue part from that proposal and added this specific topic as a more actionable issue instead, just mentioning it and also its related sister issue #60418 as case examples where the lack of proper tooltip APIs are an issue.

The proposal #66993 itself is a bit more broad and includes a suggestion of providing an built in app level toggle to enable and disable tooltips.

flutter doctor -v
[√] Flutter (Channel beta, 1.24.0-10.2.pre, on Microsoft Windows [Version 10.0.18363.1139], locale en-US)
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