The Bug:

Additional health is always displayed as absorption hearts on the tab list.

Steps to Reproduce:

• Create a scoreboard objective for tracking your health and set it to display on the tab list.

/scoreboard objectives add health health
/scoreboard objectives setdisplay list health

• Set your max health to a value of 22.

/attribute @s minecraft:generic.max_health base set 22

• Heal yourself so that you have full health.
• Press TAB.
• Look at your health on the tab list.
• →  Notice how the additional heart that you have on the tab list is displayed as an absorption heart despite not having the absorption effect.