I like Solid Explorer personally, I guess if you want an easy fix use a different file manager
It shows up everytime I power on the tv with a usb drive connected
put a check in that box, then hit ok. that should stop it.
Go into that apps notifications and turn it off or simply get rid of the app.
Either look in file commander settings to disable this, or uninstall and use a different app. X-plore works fine and has useful functions, but it's not free
I have the same issue with Stadia when I connect the Stadia controller via USB-C to play other services. And it won't remember my decision.
lol this irritated me so much that I started using Plex. I got a raspberry pi, installed plex, and put the drive on that. As a bonus I get a ton of metadata about things now, and for kicks I got a pihole too. Maybe too much work to get rid of the dialog, but I'm super happy with the result.
USB OTG enabled ? In File Commander settings there is a setting USB OTG Autoplay.