On the right I changed the size to world (with maxscript) and the strange light leaks are gone.
The thing is that with new settings it’s not possible to change that in UI, so I guess that screen size is the recommended setting. But even with higher subdivs the light leaking is present. Here’s the same thing with 2500 subs:
They look like glossy reflections to me.
If i turn off the specular component, the image renders as attached.
If you consider this leaky, would you kindly point them out, Tomasz? (not being testy, just we may have differing views of what is good and what isn’t.)
The scene I sent might have Light Cache size changed to “world” and as I pointed in my first post, the leaks are gone there. Try default settings with “screen” type.