Reproduce
Change player's attribute via command
/attribute @s minecraft:generic.max_health base set 1.0
Die and respawn
/kill
Check the attribute
/attribute @s minecraft:generic.max_health base get
The value is 20.0f as default rather than 1.0f which is expected.
This bug is related to MC-16773 to some extent, when Adams implied this may change after "we have more control over how attribute modifiers are applied." But now we still don't get a method to keep a changed attribute value during respawning, though attribute command is provided.
Linked issues
Comments

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Duplicate of MC-179940