My character is taking damage when going through the nether portal, that shouldn't be happening

What I expected to happen was

I expected to not take any damage when entering the nether

What actually happened

I didn't expect to take damage when entering the portal

I took damage when entering the portal

I took damage when in the loading screen of entering the nether

Steps to reproduce

1. Build a nether portal
2. Light it and enter
3. Wait for your character to take damage upon loading in the nether (via the nether portal that you built)