There is a recent change in bank transfer, my question is what do they mean? 

I just view my statement, and I have an online transaction for 2.1 million baht (Credit+Debit) within 3 months however just less 50 transactions. 

Will I be subject to this tax review?

 

'Under the bill proposed to the NLA meeting yesterday (Dec 4), financial institutions will be required to report transactions of customer accounts which receive either more than 3,000 deposits and money transfers a year or more than 200 deposits and money transfers with a total value of at least B2 million a year to the Revenue Department. The bill amends the Revenue Code.

Lawmakers later agreed to redress Section 3(2) to increase the threshold from 200 to 400 transactions a year with a total value of at least B2mn.'

Read more at https://www.thephuketnews.com/new-tax-law-to-see-online-bank-transfers-to-be-monitored-69571.php#kfRuLh0tmPqXzYb6.99

Anybody?

You should be fine...the BKK post article that Phuket News referred mentions 2 distinct criteria, the second of which says "400 or more transfers per year totalling at least 2MB" in total. Therefore it appears that you haven't yet triggered the review criteria.