ghk-cu collagen synthesis wound healing is getting a lot of attention right now, and for good reason. This is not just a “skin peptide.” It's a copper-binding tripeptide with documented effects on gene expression, Figure 2 from GHK –

Sun protection: Protecting your skin from the sun is crucial, as depigmented areas are more susceptible to sunburn

TUEs require the compound to be a licensed medicine with documented medical applications

second permeation enhancers along with Transcutol P provided enhanced release pattern as provided under example 2

[8] With that, the electricity required is closer to 1,712 kWh of electricity per day

It simply means the peptide hasnt gone through the multi-billion-dollar approval process that only major pharmaceutical companies can afford, and there is ZERO incentive to raise funds for a naturally occurring compound