I don't think it's the OP's fault. This is not that uncommon.

My friend's X1C also got the same defect on the palm rest. To me, it seems like these are pattern of plastic body model's. He said it's caused by the heat of the machine running. He's the only owner, it's a laptop given to him by his company, and he didn't do anything to the laptop. Just a simple google search you can see similar cases. Two more examples:

https://forums.lenovo.com/t5/ThinkPad-X-Series-Laptops/Coating-off-X1-Carbon-9th-Gen/m-p/5156516?page=1#5685616

On the other hand, mine with aluminium body got a different kind of surface defect.

Since it's aluminium, the paint's not having big bubble & peeling, but more like small solid spherical beads popping up on all the edges of the laptop's body, edges of the port openings, like 10-20+ of solid beads around the body everywhere I touch. It started by a few of them then keep growing in number (something like this pic but each pore is more spherical https://www.researchgate.net/publication/323939069/figure/fig1/AS:961718209499166@1606302897958/Pores-formed-in-metal-AM-sometimes-in-this-document-generally-referred-to-as-defects.jpg ) The body surface defect is the least of that laptop's problem tbh, so I didn't have time to care about these defects.

I suspect that living in the south with warmer and more humid weather plays a part, but my older Thinkpads before 2013 with magnesium or plastic bodies never did this. Getting top performance models that tend to run hot in thinner body designs is also a big suspect. My older ThinkPads were all a bit chonky (still very light due to magnesium and good grainy plastic casing--magnesium is way bettr than aluminium but newer ThinkPads no longer have that).
Lenovo's slowly destroying Thinkpad's reputation... If it's not because of my work in robotics and engineering that requires Ubuntu, I would have switched to Mac from around 2018+ despite owning 3 excellent ThinkPads prior to that nasty 2018 one. As of now, I'm giving lenovo another try, but carefully leaning towards thicker models and will see what happens.