You’ve got crepitus (bone crackles), which is caused in one of two ways: arthritis, where a worn-down meniscus means there’s bone rubbing on bone, or little gas bubbles in the synovial fluid that burst when you move the joint. If you’re not feeling pain, then it’s likely *not* arthritis (but please don’t quote me on this! That’s something your OS can/should confirm/dispel), but just popping bubbles.
I had a bit of crepitus in my affected knee, but it kind of resolved itself. Not a big deal or anything to worry about.