Following up, I was sitting just shy of 4k miles to requalify for Diamond when covid began. My origianal expiry date was May 2021. When that happened, they extended the date to May 2022. And earlier this year, I messaged them to confirm the details and they said they would further extend.

Specifcally- they ended my qualification period by a full year to 2023. I was still just short of 4k miles to renew so they didn't reset that counter. Funny enough, I recently took a work flight so I actually have enough miles to requalify so I'll see what happens next year.