Is this causing the remote to produce an audible tone, or just giving an annoying indication on screen?
This looks like the "Gaming Remote" (A and B keys) that came with my old Roku 3, although I don't see the Roku 3's headphone jack on the left side. I don't recall this remote having a speaker for a "find lost remote" feature, but it does connect via Wifi like today's voice remotes, so maybe...
If the Roku restart suggested above doen't do it...
Grasping at straws here, but, but might you have accidentally triggered the find remote function via the Roku Remote app?
- Select Devices on the navigation bar at the bottom of the home screen.
- Tap on your Roku device to connect to it.
- Tap the 3 dots in your device for additional options.
- Tap Ping Remote.
[My old Streaming Stick 3600 is the only one of my devices that does not show this Ping Remote option. It might be that this model doesn't support the function (?)]
This should only go for 120 seconds if no key on a remote that supports this function is pressed before then, with an on-screen countdown. But who knows what it would do if it detects a uncommon WiFi remote that doesn't support the lost remote function and tries to find it? Perhaps triggering this will force it time count down and time out.