When under ice while in survival, if you try to swim up, you are right under the ice but you don't have breath bubbles (it is like you are not even in the water)
Linked issues
Comments 2
Duplicate of MC-48395 - If you have not, please use the search function in the future, to see if your bug has already been submitted. If you could not find the original report, please comment with the keywords you searched for.
This is very similar to something I just reported. (see MC-48681)