To clarify, is the neck joint failing at the top or at the bottom? If it's at the bottom, it might be slightly weaker where the filaments change. The new version will be stronger either way, but this is good info for me when making future designs :)

I'll make a few updates to strengthen the neck joint + fix a few other issues I found and then I'll let you know when I re-upload it. I'll keep it at the current size though because it's cuter than I expected when it's that small (this should be roughly the size of the end of your thumb ~37 mm). If you continue to have issues with this new version, then I would suggest scaling it up.

What slicer/printer are you using for this?

Thanks for letting me know!

Well, this is embarrassing. I actually made a few mistakes prepping this model for upload.

1. I intended for the model in the 3MF to be twice large as large, but it looks like I accidentally scaled it down at some point. Surprisingly, it still prints well for me at that size. You're right, the neck joint should be stronger at its current scale,
2. The tail joint is fused a little bit at the top. I thought I fixed this, but I guess I messed up somewhere at the end