When using the Two Factor Authentication plugin (link) there are a few UI and user experience issues that could be improved. I was redirected by the author of this plugin to report these here. See my original report: https://github.com/nickv-nextcloud/twofactor_nextcloud_notification/issues/343
Multiple problems:

Client version: Version 2.6.4stable-Win64 (build 20200303)
Operating system: Windows 10 or MacOSX
OS language: Canadian French
Installation path of client: C:Program Files (x86)Nextcloud
Nextcloud version: 17.0.7
Thanks for the report.
It turns out we changed things quite a bit in the GUI lately and some of what you report seems tied to the GUI (not all of it though). Could you try out one of our daily builds and let us know how it's doing there?
You could for instance use: https://download.nextcloud.com/desktop/daily/Windows/nextcloud-2.7.0.15534-daily-20200622-Release.exe
Thanks in advance.
I'm now running the Nextcloud client 3.0.1 so I was able to try what you asked for.
I would say, it's a worst experience unfortunately.
This makes the Two Factor Authentication plugin completely nonfunctional :(
Isn't it a duplicate of #2339 ? (that second one is more recent but provides more 3.0 related context)
I agree that #2339 is better to describe attempting to accept the login attempt. But the other problem (that you don't receive the notification on Windows) is a separate problem. Maybe I should open a separate ticket?
Ah you mean it's not even in the activity list on windows? This would be surprising, or you're talking about a native passive popup notification?
What I mean is that, other that the entry that silently appears in Nextcloud's activity list, there's no other notification. Basically, there's nothing that direct me to open Nextcloud's activity list.

Fair enough, that'll likely be fixed with #2486
I'm now running the Nextcloud client 3.0.1 so I was able to try what you asked for.
I would say, it's a worst experience unfortunately.
* No notification is received on Windows (my phone received the notification immediately though) * There is no way to accept the login attempt in the 3.0 clientThis makes the Two Factor Authentication plugin completely nonfunctional :(
I am having the same issue on 3.0.2. I don't use the Windows notification system so the 2FA notification system on Desktop is unusable.
Everything, except this part "The Notification on Windows or macOS is not received until the user opens the Nextcloud client and navigate to the Activity tab" is fixed by #2666
To make the OS notification appear immediately, without having to open the app's tray window, we need to implement push notifications first. Those are not on the roadmap at the moment.
Please, create a separate issue about that.
Here is a small workaround I offer until we got the push notifications implemented.
You just need to add a property into a config file of your Nextcloud client desktop app.
Kindly find the file named nextcloud.cfg in your AppData folder (for Windows it is in C:Users
Add the following snippet one-line before the [Accounts] section:
[Nextcloud]
notificationRefreshInterval=60000
This will allow a notification query to run every 1 minute (it's the lowest value possible).
Be advised, this may increase the load on your server depending on how many desktop clients will have this option changed and how many clients are online simultaneously.
Otherwise, you may as well disregard this setting and just open the tray manually until we implement push notifications.