the largest Memorial attendance ever recorded by a significant margin
Why would that be surprising? It has never been easier, literally, to attend the Memorial.
Log onto the Zoom meeting from your living room while wearing your robe and fuzzy slippers. Go ahead and eat & drink the emblems if you like, with your camera off no one will ever know the difference.
I expect their numbers will bounce back in 2021
Why? The restrictions on door to door are still in effect in 2021, and most likely will be in place for at least the first part of 2022.
No door to door = no return visits = no new Bible studies = fewer new publishers. Not to mention COVID itself killing off JWs at a higher rate than the normal death rate.
Numbers will continue to be down. Not the "collapse" that many on this site eagerly anticipate, but a slow, leaky-balloon deflation.