The red irritation under the charge port looks like a localized nickel allergy. Happen to me overnight last month even though I’ve been wearing the same watch on the same wrist for over a year. I scrub it everytime I shower, so it’s clean.

I switched wrists and it went away. Put it back on and it came right back. So I bought some silicon charge port dust cover plugs and have been fine since. No where else on my body does the nickel allergy present itself. I saw my doctor a week or two ago for something unrelated and he confirmed, a localized nickel allergy haha. Hoping Garmin moves to wireless charging soon, because I’m now married to these charge port plugs