Q.Potted Kumquat tree
I’ve had a potted kumquat tree for many years. Just recently the leaves and fruit have been dropping off rapidly. In summer it is on the south side of our home and gets water every 2-3 days because the Oklahoma sun can be brutal. This is the first time we’ve had any problems with the tree. I suspect it may be root bound, as it’s been in its current pot about 4 years. The tree is approximately 5-6 ft tall. Could being root bound cause the leaf/fruit drop or is there another problem I need your help with to identify?
Thank you,
Alison Anderson

Yes, it very likely needs repotting, as a Kumquat Tree does not like to be root bound.
This article has more information for you.
https://www.gardeningknowhow.com/edible/fruits/kumquat/growing-kumquat-trees.htm