Monstera: Scale or corking?

Hi all. I can’t tell if this is corking or scale? When I scrape it off to get to the “bottom” it looks like I’m going right on to or slightly into the surface of the plant. It’s like a tan-greenish color when I scrape it off. I think it’s corking but not sure. This plant has been indoors over the fall and winter but under grow lights. It has recently lost some leaves – all from the bottom and older. Two more leaves are on their way out. However, there are in close proximity to 2 burgeoning offshoots/branches. All of the leaves that have come off in the past month and are currently yellowing are approximately 2-3 years old. I don’t see any other signs of disease. Water about once a month or so (will increase frequency now that it’s outside and warmer). Water 2 days ago. Now under bright, indirect light outside.