It is just environmental damage from sun or wind burn. Maybe they need to be protected a bit more to prevent additional damage.

Dave

Thank you Dave. Should I take it a bit slower while Hardening them off?

thanks for your help

Most of the advice I've seen on hardening off is to take it gradually, giving the plant a chance to adjust itself to the harsher elements outside. Starting with a couple hours/day up to full time after a couple weeks. Your plant should be fine

Can't really advise on "taking it slower" as I don't know how you were doing it. But it isn't so much time as protection. An indoor grown plant set out in the direct sun on a windy day for even 1 hour can be damaged or even killed. The same plant set out in some light shade with something to bock the wind from hitting it could go 3-4 hours with no damage. The process of hardening off has to be gradual in both time AND level of protection.

Dave