I'm still pretty new to modeling and rigging, so apologies if this question seems obvious. But I tried to apply a skeleton and rig to a mesh I was working on. Things seemed to be fine, until I switched the rig from Rest Position to Pose Position: before I had even made any changes to the rig, it deformed the mesh heavily. The face seems to have been hit the hardest, sagging and being pulled forward around the mouth and eyes.
If it helps clarify things, I set the rig as the mesh's parent using the following path: "Parent>Armature Deform>With Automatic Weights". This was the Armature Deform option which seemed to be causing issues with mesh deformation, but it also seemed to be the mode which lent itself to posing most easily (the two are likely related, but I don't know how to troubleshoot this).
Do you have any troubleshoot options I can try to fix this, or can you otherwise recognize what the issue is? I'll attach the Blender model here for reference, in case you can find the issue here.