I have had the TTB bank app for months and like the Siam Commercial bank app, it too is simple to use, so this is unlikely to cause problems for people. Personally, although they try to tout it as a "better banking experience", or words to that effect, even though I find both apps very easy to use, I still prefer the option of deciding between using the app or using internet banking.
Today, September 14, I received the following text message written in Thai. This following is the English translation via Google Translate:
TTB would like to announce the termination of TTB Internet Banking (TTB Direct) services from October 18, 2023 onwards.
This is for a continuous user experience. You can sign up for the TTB Touch app to make online transactions more convenient.
See more details at the ttbbank website > News Room > Press Releases.