Betta Fish: Just confirming my fears, it’s getting to be her time isn’t it?

She's a bit over 3 years old, she came home over 2 years and some months ago. She's been slowing down for the past few months, and these last few weeks she's mostly been sleeping on the bottom, it seems to take a lot of effort for her to get to the surface. Little to no interest in food. Parameters are good, she's in a very well established heated and filtered 10 gal. I just need some confirmation from someone elses eyes that she is indeed starting to pinecone. If there are any ideas of something I could do to help her lmk, but with the stable parameters and slow decline over the last 6 months my best guess is just age.