Failed to allocate BUFs during DBCC CHECKDB
While I can't tell from the OLDSERVER data, it looks like NEWSERVER has at least 2 NUMA Nodes whereas I'm not sure if OLDSERVER has multiple NUMA Nodes or a single node.
Assuming, for the moment, that the OLDERSERVER only had a single NUMA Node, it does seem you're hitting a known issue which was fixed in SQL Server 2016 SP2 CU5, whereas you're currently on SQL server 2016 SP2 CU3.

An &quot;Out of Memory&quot; error can occur when a Database Node Memory (KB) becomes less than 2 percent of the target size, and it cannot discard database pages on the node anymore to get free pages.

If you look at the MEMORYSTATUS output, it does fall into this with about 1.59% of pages available, at least on NUMA Node 0.
I'd apply, at a minimum, SP2 CU5 and run the load again.