Inside the UV texture map for the normal guardian and elder guardian, there are model parts which overlap. Meaning if one part is modified, other sections will be too.
Steps to Reproduce:
Apply the resource pack:
Summon a guardian type mob
[media]
Overlap:
Total texture spaces of the different model parts:
Fin is red
Body is blue
Overlap is purple
Guardian:
[media]
Elder Guardian:
Notes:
Linked issues
blocks 1
relates to 2
Attachments
Comments 1

Can confirm:
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