Try to scrape it off with your fingernail. If it smears - its mould. If it falls - its a pest (https://en.wikipedia.org/wiki/Scale_insect ?)
The part you have circled looks like a bug. Look at leaf with the ? on it toward the end looks like a bug. The next pic down same leaf same orange looking bug, but in a different position. Second pic bottom left looks like something chewed a hole in the leaf. Spots of web or cocoon if a few places also.
O.K.Try to scrape it off with your fingernail. If it smears - its mould. If it falls - its a pest (https://en.wikipedia.org/wiki/Scale_insect ?)