This has been an issue for several months in Bedrock Peaceful mode. The hunger bar depletes just as it does in Easy/Normal/Hard mode, to the extent that you cannot sprint once the hunger bar reaches 3 out of 10 levels.

Expected outcome: Hunger bar never depletes in Peaceful mode
Actual outcome: Hunger bar depletes in Peaceful mode and prevents sprinting at 3 or fewer hunger bar levels (does not make health bar deplete at 0)

Steps to reproduce this issue:
1. Open a world in Survival Easy/Normal/Hard
2. Change difficulty to Peaceful
3. Sprint jump a bunch idk, just do a bunch of stuff that would drain hunger quickly in Easy/Normal/Hard