Hi
It's a sign of muscle weakness surrounding the joint.
Next Steps
start wearing a knee supporter while doing exercises. start doing exercises at very light pace n need to do it with correct alignment.
if there is any internal rearrangement need to get it evaluated with a qualified physiotherapist first.
Health Tips
do always warm up. followed by exercises and end stretching is mandatory.
wear knee cap for proper support.
can tape your knee joint . get it done by a Physio if problem persists.
Need to evaluate other aspects if still problem persists.