I created a nether portal in my base and went through it. After adventuring around for a while I went back through my portal and ended up in a random tree. I broke the portal in the tree and then went back to my base and saw that the portal in my base was still lit. I went through again and came back out and ended up in a different tree nearby. I did the same thing a third time and it still happened.
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Thank you for your report!
We're tracking this issue as MCPE-39609 which has been resolved as "Working as Intended", this ticket is being resolved and linked as a duplicate.
There are some intricacies to portal linking that can sometimes be misinterpreted as a bug. The mod team here as well as Mojang have done significant testing based on the reports that have been made and are unable to reproduce unexpected behaviour.
Please head over to the linked ticket which has a bunch of information in it to help with portal linking issues.
If you believe there to still be a bug, please feel free to head over to the Mojira Discord and discuss it with us in a relevant channel.
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