I was looking at my wallet in keybase, which I haven't for years. Other than the Stellar Lumens that Keybase has given away,I have under assets BTC "trustline"

I was looking at my wallet in keybase, which I haven't for years. Other than the Stellar Lumens that Keybase has given away,I have under assets BTC "trustline" address. I vaguely remember adding something to be able to receive BTC. It shows as a certain value, but it does not seem I have any agency over it. What does this mean?