I've been using Bitbucket for almost 2 years and received notification emails for all of the repos I'm watching. I stopped receiving updates roughly from 1st April, 2021. I didn't change any settings with my notifications or my email address. I got migrated to new pull request experience in mid Feb itself.
To my surprise, many of my team members are still receiving them. I'm the only one with the problem.
As a side note, my Jira & confluence email notifications work fine. It's only Bitbucket emails that are not coming through.
NOTE: I already check with client & helpdesk but nothing has changed on their end.