Every time I open the Arduino IDE I get a pop up from the library manager. When I click on it it tells me that the USB host library needs updating but there is no button to update it. I'm using version 1.8.2 on Windows 10 desktops and laptops however the bug has been around for several versions. I figured someone would report it and it will get fixed eventually but it's been a while and it's very annoying.
I'm guessing you have one of the Arduino SAMD boards selected? I agree that's extremely annoying. The sad thing is that this actually has been reported, and even by a member of the Arduino team:
I explained how it can be fixed in that issue, as well as in multiple previous reports of a similar problem happening with other libraries and boards. It would take maybe a minute to make that fix. The real fix would be to make Library Manager smarter so it doesn't do this. I can't understand why this issue has not been taken seriously by the Arduino developers. They are usually very responsive but they have absolutely ignored all mention of this. I don't even use an SAMD board and it still annoys me because sometimes the board list gets reset to the Zero and I get that notification. So until the Arduino developers get off their asses and fix it you have two options:
Turn off the notifications: File > Preferences > Check for updates on startup. This is easy but not ideal because those notifications are actually really useful when they work correctly.
Give the USBHost library a unique name in its library.properties file. I can provide instructions for this if necessary.