Black spots on this Japanese Maple

[guimeixen]

I posted a few weeks back about this Japanese maple and today I'm hoping someone could help me on what could be causing these black spots on the leaves.
It seems to have happened really quickly. I think five/six days ago it was fine and suddenly I noticed a lot of black spots appearing on the leaves.
I also have a small Shishigashira and it's happening the same thing.

 

[LeatherTree23]

Post in thread 'Black Leaf Spots on Amur Maple'
https://www.bonsainut.com/threads/black-leaf-spots-on-amur-maple.55992/post-968940

This maybe helpful.