Hello!
I submitted my i-751 case on December 3d, 2021 and today, after 17 months of waiting I finally got approved. Woo-hoo! It has been a long -XXX wait... Approval came in at midnight on May 4th Maybe something to do with Force.
It appears WAC started working on December 2021 cases, so hopefully everybody who submitted their case in that month will get approved soon.
Good luck!