The rainy season arrived this year on May 10th, which is late, and led to high temperatures. But in the "disaster year" of 2010, the rainy season came even later, on May 12th.
There was news about coral bleaching in 2010. It was great concern then. It could take up to four years for the coral reef to return to its usual self.
There are many research centers that have reports on coral bleaching. In several places, this number "four years" is cited.
A report that seems unbiased comes from the University of California. It states that a coral reef was 90 percent recovered after one year and fully restored after two years.
https://scripps.ucsd.edu/news/central-pacific-coral-reef-shows-remarkable-recovery-despite-two-warm-water-events
This study comes from coral reefs that have no significant human activity nearby. It takes longer if there is human activity. But then the problem is not the temperature, but rather things like overfishing and pollution.
The article refers to a record temperature of 32.73 degrees, according to the Department of Marine and Coastal Resources in Thailand. But that's a peak measurement. In 2010, on May 12th, a temperature of 32.09 was reported by Ramkhamhaeng University. But that was an average of various measurements.
Today we see from various sources that the temperature in the sea around Thailand is down again, around 30 degrees.
There was significant coral bleaching in Thailand in 1991. But also smaller cases in 1995, 1998, 2003, 2005, and 2008, according to the Phuket Marine Biological Center.
After the "disaster year" in 2010, there was coral bleaching again in 2016.
The bleaching is related to the weather phenomenon El Niño, which had its maximum effect in Thailand this year, but which is now expected to subside, making way for La Niña. Then it will be cooler and more rainy.