When you use Programmer Art textures, hearts become invisible and you can't understand how much health do you have. Looks like a gui file for this texture pack wasn't updated.
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Can confirm, relates to MC-205096.

I have the same issue! Made my own report but was lead here. Beat me to it ;}
Can confirm in 21w10a. Video attached.

can confirm in 21w16a
related to MC-204902
Can confirm in 21w17a.

Can confirm in 21w19a
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