Have any type of slab underwater and when you are in the swimming position press A to make your character stand up, once your character stands up it should phase through the block.
Linked issues
duplicates
Attachments
Comments
migrated
[Mod] OcelotOnesie
Thank you for your report!
We're actually already tracking this issue at MCPE-72648, 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.
If you haven't already, you might like to make use of the search feature to see if the issue has already been mentioned.
Quick Links:
📓 Bug Tracker Guidelines – 💬 Community Support – 📧 Mojang Support
📓 Project Summary – ✍️ Feedback and Suggestions – 📖 Game Wiki
I have a similar issue: MCPE-81708