Modpack version
1.66c

Can the issue be reproduced?
Unknown

Logs
https://drive.google.com/file/d/1EEta31rQSbXy_3dRVd53qOFYyxSHak2i/view?usp=sharing

Issue
Upon updating the server from 1.65d to 1.66c, tile entities become indestructible by players. They can be moved with sacks of holding. Dirt cannot be destroyed without an IC2 drill. Other blocks cannot be destroyed at all.

Thank you for the report, I will investigate the issue.

I have upgraded our servers from 1.65d to 1.66c yesterday and everyone has been playing as expected. I wouldn't know where to start debugging this without more information.

Downgrading to 1.65d allows the server to function as usual. I was running SpongeForge-2838-7.1.7-RC3859 along with the Nucleus, LuckPerms, CatClearLag, and MagiBridge plugins. No anomalies appear in the server or client console upon attempting to break a block.
I've also discovered that mobs, after being hit once, cannot be hit anymore.

I've tried removing Sponge, but the issue is still extant.

That's quite the deviation from the stock setup; does the issue also manifest itself when using stock E2E? I don't have a Sponge setup with the additional plugins, so I can't reproduce this.

Seems to have been fixed in SpongePowered/SpongeForge@156f70c. I launched the server adding the updated Sponge and all issues have been reversed. Thanks and apologies for any inconvenience.