So, i thought this was already reported but as i continue to see this bug even in newer versions im going to report it,

in 1.13 you added that warm ocean biomes spawn near warm and hot land biomes and cold ones with cold ones but i continue to find coral reefs and luke warm oceans next to snowy plains and Ice bergs litterally next to deserts

at first i thought it was only on minecraft pocket edition but now i found it on java too,

my only guess is that you accidently put cold biomes spawning next to hot ones and vice versa