FWIW, I had to go to BKK CW last week in order to get my stamps transferred to a newly issued passport.
As part of that process, much to my surprise, the IO there required me to do TWO things that normally are only required for new extensions -- provide photocopies of my bank passbook pages covering the past year, and update my bank passbook that day to show the current balance.
I don't think they ever required that bank stuff last time I got a new passport 10 years ago. But last week, at BKK CW, I checked with a supervisor, and she confirmed that the bank book update and bank passbook photocopies now are going to be standard requirements anytime any of us with extensions based on Thai bank deposits are doing ANY business with the L section there.... (and that includes merely having stamps transferred to a new passport).
PS - In my visit last week, I had TWO bank passbooks, a full one that ended a few months back, and a new one covering the past couple months. And the IO who handled my stuff wasn't troubled by the notion of my having two bank passbooks for the same account, each covering a part of the year. Nor did they require a bank issued 12 month statement, and were fine with my photocopies of the pages from both books.