Update of server today to 1.21 has caused huge terrain corruption

These massive structures are all over my map. One wall I followed in creative mode stretched for 1500 blocks. I believe this world was created in 1.19, not too very long ago as we are fairly new players, but I think we need to roll back as having so many impassible walls is not going to be much fun. One anomaly would be ok, but this appears to be everywhere. 

My seed is: 5845141558424835359