As the title says, I pushed the sim pin into the mic hole, exerting some pressure before realising it was the wrong hole.
Very careless of me, but the mic works fine, but will it have damaged the waterproofing?
The holes are too close to each other!
My FInd X3 Pro was developing a tiny black dot on the screen, and it was still under warranty with days left, so I booked it for repair. The technician was repairing my phone right in front of me, and he poked the wrong hole while ejecting the sim card as well

JerryRigEverything pointed out this issue on one of his YouTube videos.. and he tried it on various brand of phones, and all of them were safe after the microphone hole was violated by sim card ejector tool.
All of the manufacturers tested on the video designed the actual waterproofing mesh and microphone itself on top or bottom, perpendicular to the shaft, not at the end of the shaft. Some manufacturers even made the shaft gets smaller so the ejector tool can't get to the very end., but for those which the ejector can make it to the very end, its still safe and the waterproofing membrane still intact.
Oppo wasn't one of the phones tested, but OnePlus was, and I can't imagine Oppo is doing things differently.