It is unclear if it's specifically Apple Watches that are causing rashes and burns to users' hands. There is no explicit statement made by Apple themselves, instead are comments made by users posted on Apple Community forums. One user on the Apple Community forms have stated, "Hello, this is not an Apple Watch issue. I do not own any Apple products, but came looking for "Apple Watch Wrist Burn" and landed here, because my Garmin watches have done the same thing three times. Replacement of the watch doesn't really help...".
Other sources also tend to be secondary news websites or blogs which provide recommendations on how to handle the situation. For example blogs like BodyGlide which states, "Apple Watch rashes, often dubbed “Apple Watch dermatitis,” can arise due to various factors. These may include allergic reactions to materials in the watch band, friction from constant contact, or moisture buildup between the watch and the skin".
It seems that wearable wrist technological devices present an occuring phenomenon with rashes or other forms of skin irritation. Yet, it remains unclear if there is acknowledgement from Apple themselves providing reasoning or possible recalls for such problems. For now it seems that the community demonstrates it as a occuring problem exemplified with Apple Watches.
https://discussions.apple.com/thread/254255279?sortBy=rank
https://bodyglide.com/blog/apple-watch-rash-and-how-to-deal-with-it/?srsltid=AfmBOoqTZUFyOyWE3T2iTAsX9VM9uVQS_b931QX4AwG6oZ6EhfhRgL5f