Japanese Holly (Ilex Crenata) leaves problem

In the last couple of months the leaves on the lower branch of my Japanese Holly have started becoming spotted and are now falling without regrowing (picture attached).
Leaves are also slowly turning spotted on the upper branches.

The plant is internally positioned in front of a east facing window.

Does anyone know if there is any action I can take to reverse this situation?

Thank you

scale ?

i would take it to a local garden center or bonsai club and have it looked at in person...