[jewel]

I've heard it called "Platform risk". Also "Playing in someone else's walled garden", or something along those lines. I realize that's not a term for the inevitable rugpull, but that's the closest I can think of.

[amelius]

Building your castle in someone else's kingdom.

[theolivenbaum]

And obviously the Germans have a word and a law for it: Erbpacht (https://de.m.wikipedia.org/wiki/Erbpacht)

[oldsecondhand]

Building your mobile home on rented land.

[d13]

You live on that platform, you die on that platform.