The specific number is the clue here, and it points at the measurement rather than the hardware.
60Hz is almost exactly a typical display refresh rate, and browser gamepad polling is commonly driven by the page's animation frame callback, which is tied to refresh rate. A reading that lands on 60Hz, rather than some arbitrary degraded figure like 173Hz, strongly suggests the page is now sampling once per frame at 60 frames per second instead of running at full rate. A controller that was genuinely failing would not conveniently land on your refresh rate.
There are a few things that cause this and a Windows update can trigger all of them. The browser may be throttling the tab, which happens if the window is not focused, if it is partially obscured on some configurations, or if a battery saver or efficiency mode has been switched on. Windows power plans get reset by updates fairly often, and Windows 11's efficiency mode throttles background tabs aggressively. A graphics driver update can also change your display's refresh rate back to 60Hz, which would cap frame-driven polling at 60 regardless of the controller.
So check in this order: your display refresh rate in Windows display settings, because an update resetting it is very common and it would explain the number exactly; then your power plan and any battery saver; then test with the browser window focused, maximised and in the foreground.
If after all that it still reads 60Hz while your display runs at a higher refresh rate, then look at the controller: reconnect it, try another port directly on the motherboard, and check whether 8BitDo's utility reports a polling rate setting, since several of their pads expose one that a firmware update can reset.
And for reassurance on the practical side: even if it were genuinely 60Hz, it would be unlikely to affect how the controller feels in a game, for the reasons in our polling rate guidance. But a four times drop is worth understanding rather than ignoring, and you are right to ask.
