Max it looks like you hit something in the old bit of plywood. Your feeds and speeds are high, but I'm not going to comment on them further. If I cut timber I normally run around 1200mm min at 10 to 20k rpm. But timber is really forgiving. Carbide is brittle but hard. Is there a chance you dropped the end mill?
Mate. If I bought a carbide end mill for $$ and ran it like you had. Had definitely not hit anything. I would be sending a pic to the supplier.
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