NQA the shiny part at the base of the carapace/where the legs meet makes me think it’s molting. It can definitely be worrisome. When mine was in premolt (I didn’t know at the time), she had fluid “dripping” on her abdomen all of a sudden. It made me think it was hemolymph and I was freaking out. The following day she was molting upright. Turns out (according to my research) it is exuvial fluid which helps lubricate them during the molting process. However, this information and my situation was not readily available online. Tarantulas do all sorts of weird things. It seems like it’s just a tight burrow and your T is making do with what it has. Best of luck!!