The dig did not show that the tunnels were the king's palace.
Debated. The passages are only believed to be Tudor.
They are under New Hall School in Chelmsford, Essex. The school stands on land King Henry VIII bought in 1517. Workers found a brick-lined underground passage while they mended a sunken ditch. They also found pottery, animal bones, glass bottles, and bits of crockery. Those finds are believed to be Tudor.
The page is not sure if the tunnels stored things, or only held rubbish.
https://www.ancient-origins.net/news-history-archaeology/tudor-palace-tunnels-00102877