If it's very long, I'd suspect that it's being physically distorted during the installation process since the glass itself is flexible enough to distort the image without breaking first. To correct it, you need to make sure that the mirror is as straight as possible - use shims.
If it's along a wall, the mirror may be following the contours of a slightly uneven wall. You can shim the back of the mirror in the hollow spots to correct this. Masking tape (ideally the blue kind to protect the mirror) can be used in the low spots to build up sufficient support for the glass. Thicker shims can be used if you find the hollow spots to be very thick.
It's it's in a frame of some sort, either the frame is not straight, or it is sagging/distorting too, or (if the glass is sufficiently loose int he frame) the mirror itself is just distorting as above. The approach is basically the same - shim the spots that you need to push forward.
Real glass is not flexible.
If the distortion is in the glass, there is nothing you can do.
I received some good ideas from others
You cannot fix it. Return it and get a new one.
Why would l do that? I have had the mirror for years!
Dottijo already posted a great idea.
Not aware of a way to fix the distortion, however, if you are looking for ways to reuse the mirror, you could cut it down with mirror cutting tools to a smaller size and frame it, etc.
Are you able to post a picture of it? I’d love to think of more ideas! ... maybe even adding some wooden embellishments that you can buy in the wood section at Lowe’s, etc. would work depending on where the distortion is
I would repurpose by painting, flowers, a scene, an etched saying
Great idea! That would help cover up the distortion. The mirror & frame is beautiful so l hate to throw it out.
I thought you were,asking how to get rid of the distortion. You're right, the old glass is great, I love it. Had it in most of my windows and a few mirrors. Always sad when one got broken. Dottijo ideas were fun. If the silvering gets too bad you can always have it resilvered. Keep on enjoying it.
We had a mirror that was looking bad and put a stencil on the back of the mirror, traced that image and used a dremel to grind the paint off the back. Then applied black spray paint. That makes the outline stand out against the mirror. Now looks a piece of artwork and have never seen another one like it.
Sounds nice & a great idea. Thank you.