I have a 2003 Honda Civic with 250k miles with a auto transmission. Recently when going low speeds when I let my foot off of the accelerator my car slows down more than normal like it’s downshifting when it’s not suppose too and it makes a weird grinding noise but it only does it when I let my foot off of the petal and it only does it when the car is warmed up. Other than that it’ll shift fine and doesnt slip. Tranny fluid was changed about 10k miles ago. What could the problem be?

First thought is bad transmission output bearing. Heck that is my second though too..

Its the size of a large hamburger patty and there is two of them, one on each side of the differential. If one is gone, you would could see a marked increase in drag and noises and being loaded vs unloaded would cause enough movement to make it audible or not.

Pull a sample of transmission fluid and see if you can see any shimmering in it. If it is a bad bearing, your transmission will likely “break” on you so I would not trust the car past a comfortable walking distance home.