I'd ease up on using the Vintage mask - see 2nd comment. -Phil
I honestly don't have any idea what you're talking about.
Most cameras offer a series of basic "Scenes" snow, sun, night, cloudy, portrait, etc. These are dialed in on the camera before the shot and optimize the settings. The next level are filters and these are nearly limitless. Some can be applied with the camera's software - after the shot is taken, while others are used in post. What I'm seeing in several of your recent photos are the result of a "Vintage" filter, and are intended to make the photo look very old. The most common method is to alter the borders. They can look worn, burnt, deckled, darkened, etc. Very common is the Vignette in which just a narrow strip along the edge is darkened, and it's also made as a gradient that's darkest at the edge and quickly drops to zero. Some filters are equal around the edges, while others can be oval or round, and a few can just darken the corners. This corner filter is what's being done to your otherwise excellent photos. -Tao of Photography
This is a screenshot made with Photoshop's "Threshold Tool". It's a Luminosity tool that works by determining whether or not a pixel is empty -white or contains anything else -black. A slider lets me smoothly select from from white to black and shows me where there are light or darker areas, as well as sharp edges. It shows that the four corners are darker than the rest of the photo, and this darkness is the direct result of a filter being applied somewhere in the photostream. -Tao of Photography
So do you mean vignette? I don't know what "vintage mask" means.
Vignette is just one technique, while vintage is the many ways of making the photos look old. -Phil
Jess, something is messing with some of your photos. I picked 18 out of your Pixelfed timeline that show the masking. This dual screenshot shows two hard-edged elliptical masks, which are NOT accidental [I make these to order for classical portraiture]. If you're not tweaking your photos [which I recommend you should do and is perfectly A-OK], then there's some step in your photostream that's doing it. If you want to dig into this, I'm certainly up for it! The first step would be to send me the EXIF file from the "Raven" photo. The EXIF files are stripped out by Pixelfed in order to protect the innocent. -Phil