diff --git a/src/PIL/WebPImagePlugin.py b/src/PIL/WebPImagePlugin.py
--- a/src/PIL/WebPImagePlugin.py
+++ b/src/PIL/WebPImagePlugin.py
@@ -311,9 +311,11 @@ def _save(im, fp, filename):
     lossless = im.encoderinfo.get("lossless", False)
     quality = im.encoderinfo.get("quality", 80)
     icc_profile = im.encoderinfo.get("icc_profile") or ""
-    exif = im.encoderinfo.get("exif", "")
+    exif = im.encoderinfo.get("exif", b"")
     if isinstance(exif, Image.Exif):
         exif = exif.tobytes()
+    if exif.startswith(b"Exif\x00\x00"):
+        exif = exif[6:]
     xmp = im.encoderinfo.get("xmp", "")
     method = im.encoderinfo.get("method", 4)
 

diff --git a/Tests/test_file_webp_metadata.py b/Tests/test_file_webp_metadata.py
--- a/Tests/test_file_webp_metadata.py
+++ b/Tests/test_file_webp_metadata.py
@@ -55,9 +55,7 @@ def test_write_exif_metadata():
     test_buffer.seek(0)
     with Image.open(test_buffer) as webp_image:
         webp_exif = webp_image.info.get("exif", None)
-    assert webp_exif
-    if webp_exif:
-        assert webp_exif == expected_exif, "WebP EXIF didn't match"
+    assert webp_exif == expected_exif[6:], "WebP EXIF didn't match"
 
 
 def test_read_icc_profile():

EXIF prefix saved in WebP
### What did you do?

I saved 2 copies of a webp file, one with exif=exif_bytes as shown, one without, then added the exif data by piexif.insert

### What did you expect to happen?

exif data to be the same

### What actually happened?

winmerge binary comparison reveals "Exif" is quoted one extra time in the Pillow image.save version indicating a coding error

### What are your OS, Python and Pillow versions?

* OS: Windows 10
* Python: 3.8
* Pillow: 9.2.0

<!--
Please include **code** that reproduces the issue and whenever possible, an **image** that demonstrates the issue. Please upload images to GitHub, not to third-party file hosting sites. If necessary, add the image to a zip or tar archive.

The best reproductions are self-contained scripts with minimal dependencies. If you are using a framework such as Plone, Django, or Buildout, try to replicate the issue just using Pillow.
-->

```python


from PIL import Image
import piexif
import piexif.helper

info = "test data in User Comment"
fullfn = "sample_image.webp"

exif_bytes = piexif.dump({
		"Exif": {
			piexif.ExifIFD.UserComment: piexif.helper.UserComment.dump(info, encoding="unicode")
		},
	})

with Image.open(fullfn) as image:
	image.save(fullfn, quality=60, exif=exif_bytes)

	image.save("sample_image_inserted_exif.webp", "webp", quality=60)

piexif.insert(exif_bytes, "sample_image_inserted_exif.webp")

```

