Commander Token rules.
I have a commander that makes tokens when you put -1/-1. Counters on a creature, but it doesn't create those tokens when I use anything other than the commander, but the card doesn't specify that it needs to be the commander to create those tokens. There are a couple cards in MTG ARENA that have bugs.

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Rezzahan#77802 commented
-1/-1 and -1/-1 counters are two different things. The first is a temporary continous effect that lasts for the stated duration. The second is a marker with inherrent power/toughness modification that is applied for as long as that counter remains on the permanent.
Eyeblight Assassin only gives -1/-1, not counters.
You can easily determine which cards give counters, because they use the word "counter".