What should I do when transferring my DTV visa to a new passport due to damage?

They transferred your entry stamp and acknowledged your old passport, they did nothing with your visa itself so make sure you hang on to it

Where is the passport number written on the DTV stamp?

I had to change passports (old one was full) and it's hit and miss. Mostly I just hand the print out of my DTV and if you smile and are polite they'll be obliging. But every now and again you get someone (Thai IO) who's either having a bad day or just looking for a fight, and they'll make it difficult. But having re-entered into Thailand on my DTV at least 20 times I've always got through with just the new passport. There is no facility for Thai Immigration to transfer the existing visa to the new passport number. Seems a blatent miss by them (to me), but it is what it is.

if you would be so kind, then could you upload a scan or photo of this ink stamp you received from your local Thai Immigration Office inside Thailand, redacting any personal identity information

Also, do you mean you had a DTV Visa STICKER from the Thai Embassy/Thai Consulate physically in your old passport, or, do you have a DTV E–Visa PDF File that you printed out as a Hard Copy Paper???

Just like any other visa in any other country. You just transfer it to your new passport. Done it a few times with a new passport when the old one was full. Why would you need to carry a clipped void passport as well? The advice from some people🤣

Did you get a new 180 days stamp in your new passport? Did you show visa?

I'd still carry both for the next 4-5yrs, congrats on smooth sailing this time through.