PSA: Arrow Glacier activates next week and it has not been tested on any testnet

It is anticipated the hardfork will go smoothly without testing it because it only postpones the difficulty bomb which is something that has been done before. In any case devs have shown they are able to react swifly if anything goes wrong to minimize damage and return things to normal fast.

More on Arrow Glacier https://blog.ethereum.org/2021/11/10/arrow-glacier-announcement/

Expected activation December 8th, block number 13,773,000