Different Transactions / read write lock

Locks or Index had a cardinality change (got corrupted or even un-corrupted).

Were you running it on your own box and heat sink started coming away?

It’s because your tmp disk is full

The other way around is even scarier.

This is me, last week.

Someone drop an index?

Your query broke something. Added a bunch of garbage rows or messed up the indexes or deleted stuff you weren’t expecting it to. The database definitely changed. Hopefully you have someone at your organization who can troubleshoot the query and figure out why (probably not that hard). In the meantime, hope you have regular backups to restore from. Next time deploy to a test environment first.

Most probably some other large update is happening on the table

Have DOGE unplug their stuff.