Those fixture are most likely tinned copper conductors not aluminum.

Very unlikely to be aluminum leads.

Tinned copper is the most common fixture wire.

If you are not sure, take a knife and scrape a strand and see if it is copper colored under the plating.

While I tend to agree with brick and salt, NOTHING coming out of Communist China surprises me, and I mean NOTHING.

Please report back with what you found. Most of these new "push-in" type connectors (e.g. IDEAL brand) are listed for use with stranded COPPER wire... just pre-twist the strands very tightly before inserting, and check the see-thru portion to ensure all strands were "captured". Personally, I'd solder-tin them first.

If it turns out you really DO have aluminum on your hands, and you don't want to get a refund, then you're on a quest to find an electrical supply house that carries wire-nuts or connectors or splices listed for mixed Cu-Al use... pretty sure Duh Big Box stores do NOT carry such.

WAGO brand "Lever-Nuts" are the simplest-to-use, easiest to RE-use (but most bulky and expensive) of the push-in connectors. Because there's no force on the strands until you press-down the locking lever, you don't even have to pre-twist stranded conductors. But again, listed use for COPPER ONLY.

If you ever have to remove this ceiling fan/fixture, even to paint, the Wagos make it almost as simple as a plug-in appliance. Just used them in GF's rental flat to install way-cool chandelier. If/when she moves, landlord's lame-o pendant gets swapped back in approx. 3 minutes flat. ;')