When you revisit a topic, not only will you be taken directly to the first comment you haven’t read yet, but also it will now show a red line showing your prior visit, so you can scroll up and down without losing track of what you had last read.
When you upload images, it will now limit you to file extensions that are allowed, so that you don’t try to upload and then be told that it was unsupported.
Although there is a new feature for optimizing images in the browser on upload, for a faster upload experience and reduced data usage (particularly useful on mobile), it reduces the available resolution in larger images, so clicking in to look at details is limited.
We will want to test before any choice to enable it generally because often enough we need to look at an image at full size to see important details. We have enabled this feature with a generous configuration and may modify the configuration over time.