Chosen Solution
I recently descaled my keurig and also cleaned the needle with a paperclip. It will brew a full cup only when there is nothing in the cup holder. Once I insert a k- cup or a reusable cup it only Brewstandings a half a cup at best.
Sounds like your Keurig is stuck in the half-cup brew setting. When you brew with the k-cup inserted, some of that water is used to saturate the grounds in the k-cup, so you would get less “liquid output” with a k-cup inserted than with no k-cup inserted. Try switching between full cup and half cup setting with no k-cup installed. Is there a noticeable difference in the output from the full and half setting? If not, then it is stuck in half setting. Look at this post, to help: only brews small cups regardless of setting
