This one should be fix in the squeletalmesh quadric reduction own by the geometry tools.
Import the two attch skeletalmesh, one is having UV seams around the ears and the other has hard edges around the ears
Generate multiple LODs for the two imported skeletalmesh
Edit the material and do the same graph has the attached picture
after the material is compile and save open the imported sk in the persona editor
switch them to LOD 1 or more
RESULT: The ears have hole since the vertex color interpolation of the reduction plugin change the vertex color on both side of the "UVs seams"/"normals hard edges"
EXPECTED: The ear is still connected properly to the head
There's no existing public thread on this issue, so head over toAnswerHub just mention UE-93469 in the post.