That's an "inverted flare" fitting. Measure the outside diameter of the tubing that plugs into it and get the appropriate sized inverted flare nut. Then you'll need to find someone with a double flaring tool the right size. I was suggesting cutting the tube that goes into that fitting and splicing in a short piece of tubing to extend what's already there. You would need two compression couplings and a short piece of tubing to do that, hardware that's available at any big box hardware store.

Here's the fitting I'm talking about- - - -it splices two pieces of steel or copper tubing together:

https://www.amazon.com/LTWFITTING-Compression-Union-COMPRESSION-FITTING/dp/B00CHHY76W/ref=sr_1_4?keywords=1%2F2+compression+coupling&qid=1638507618&sr=8-4

Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
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