create and ignite a portal on the overworld
go through the portal
exit the portal quicly after generating in the nether
you will see that the fog starts of white and fades in the coresponding biome color
the fog should be the coresponding biome color from the moment you generate in the nether
Thank you for your report!
We're actually already tracking this issue at MCPE-71677, so I will resolve and link this ticket as a duplicate.
If you would like to add a vote and any extra information to the main ticket it would be appreciated.
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