Birdhists (Bird lovers) are allow to go to a tattoo parlor and ask for a Chubby Bird of their choice to get tattooed. I consider that "personal use" and I'm honored.
A commercial tattoo parlor, using them in their portfolios/walls, or online to bring in business; making money off other people's designs without permission/licensing agreement, is copyright infringement.
I'm not angry out the gate when it happens because it's not always common knowledge or maybe there's a slip of judgment. If there isn't ill intent, no reason to get mad.
If a bird lover want to toss a smol coin to their Chubby Bird artist for their tattoo, I have a tattoo coin listing.
Also, if birdhists wants more Chubby Bird references, here is the full list (I do need to add more from Kawaii Birds Book).

If your tattoo artist wants to post, it’s ok as long as they tag me as original artist. I’m @birdhism on all the major socials.

I love for Chubby Birds to be shared, just not profited off of without consent. I've put my time, heart, and soul in these little chonkers. Pls be nice when using them.