פירוש על קידושין 77:2

In the first two cases rabbis will eat orlah outside of Israel, but they will not pick it themselves. It seems that in this way, they can pretend that they’re not sure that this is orlah, and doubtful orlah is not prohibited outside of Israel.
The rabbis of Pumbedita go a step further and say that the prohibition of orlah does not apply at all outside the land of Israel.