Hello! So, since nobody else seems to have said it, I will. The Happy Ghast Spawn Egg texture is of the newer spawn egg textures even when using programmer art. That’s all. Not really sure what could be done about it, but still, enjoy. Rockatoa, Brickticks out!
Environment
Windows 11, Nvidia 4090 RTX, Java should be relatively recent.
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Thank you for your report!
We're tracking this issue in https://report.bugs.mojang.com/servicedesk/customer/portal/2/MC-169889, so this ticket is being resolved and linked as a duplicate.
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Newer textures are not updated for the Programmer Art resource pack.