Looks like Phuket has the same rules as Pattaya 800,000 needs to be "seasoned" 2 months before and 3 months after, with a minimum 400,000 throughout the year:
https://www.thephuketnews.com/holding-the-balance- phuket-immigration-clarifies-new-rules-on-retirement-visas-to-start-march-1-70401.php
I didn't know about this:
"GRANDFATHER RULE
under the new order the old provisions that people who have been living in Thailand for continually on a retirement visa since before Oct 21, 1998 can still apply under the exact same conditions that they were first approved.
Under this “grandfather rule”, applicants who are over 60 still only need to show that they either have B200,000 in a Thai bank, or receive at least B20,000 income per month"
Likewise, applicants under the same grandfather rule who are 55-60 years old can apply showing that they have B500,000 in Thai bank account or an income of B50,000 a month"