To get past the Githyanki Barrier Disruptor in Baldurs Gate 3, you need to place a Gith Shard inside it. Here are the steps to do it:

1. Obtain the Gith Shard. You can get it by either fighting for it or pickpocketing it from Captain Kith’rak Therezzyn. Alternatively, you can persuade her to let you see the Inquisitor with the information you have about the artifact.

2. Interact with the Githyanki Barrier Disruptor and insert the Gith Shard into it. You can drag and drop the item into the device, as directly clicking on it might not work due to a potential game bug.

Once you have placed the Gith Shard inside the Githyanki Barrier Disruptor, the barrier will disappear, and you can continue your quest to find the Inquisitor.