Your SSD has thermal paste that forms a bond to the upper case.

During reassembly:

Use the flat end of your spudger to scrape away old thermal paste from the top of the SSD and the underside of the upper case.

Apply a few drops of highly-concentrated isopropyl alcohol (over 90%) to the SSD and upper case. Wipe away the residue using a lint-free or microfiber cloth.

Replace the thermal pad with one that's the same size as the SSD sticker.

Alternatively, you can apply a bead of thermal paste directly to the SSD's label. Use the dot method with a bead slightly larger than the screw head securing the SSD.