If you die to a minecart with TNT that was ignited by a blaze using its fireballs, it won't count as the blaze killing you.
This issue was previously fixed in 24w44a and now reintroduced in 25w02a due to the fix for MC-278204.
How to reproduce:
Spawn a blaze in a bedrock box where it can't move, but leave a hole for the blaze to shoot through.
Place a rail on the same height as the hole, and place a TNT minecart on top of it.
Switch to Survival mode.
Stand behind the minecart so the blaze hits the minecart.
Die to the minecart.
Expected result:
"<player> was blown up by Blaze"
Observed result:
"<player> blew up"
Can confirm.
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