It’s hard to see what’s going on here, but you might try using an irrigation tool called a riser or nipple extractor – it’s designed for removing broken plastic risers outdoors, but might work if you can insert it far enough (it’s difficult to tell from your photo if the material in the center is a liquid or a solid). Have a look at https://www.homedepot.com/p/Orbit-1-2-in-and-3-4-in-Plastic-Nipple-Extractor-26076/100203404
Thanks for fixing my Lemmy notation!