The 1st issue (interior) could be due to material setup of the plant (leaves and bark) - could you show it?
Another idea is that it is caused by texture details being very small (close to 1px, or smaller), so that would be a typical AA issue.
The 2nd issue (exterior) happens when there is a reflective material (leaves) which catch sun reflection randomly. This is actually something that would happen in real life (imagine waves on the water, reflecting flickering sunlight).
The AA issues can be fixed by:
-enabling bloom and glare and blur+sharpen (defaults may work, but some tweaking may be needed), this will simply blur the pixels a little bit, but can obviously break the image for you if you are going to do some further post-processing on it
-allowing more passes to be rendered - this can be done by
a) allowing higher render time - then more passes will be rendered = better AA
b) lowering GIvsAA balance - this will devote more computing power to antialiasing than to GI, so you will get better AA, and similar overall image quality
The flickering sunlight issue can be fixed by:
-adjusting the material properties - e.g. lowering glossiness of the leaf material
-using a different environment lighting - for example an HDRI where the sun is behind clouds
-allowing more passes to be rendered for generally better quality (as explained in the previous point above)
For more info, check out:
https://coronarenderer.freshdesk.com/support/solutions/articles/5000529356https://coronarenderer.freshdesk.com/support/solutions/articles/5000501983