SQL Server 2019 Performance issue with large INSERT
From comments:
To all intents and purposes, those plans are identical. As such, I'd focus more on differences in the physical set up and server settings. If the query optimizer for 2016 and 2019 are arriving at identical plans, but, behavior is different, chasing optimizer settings, query hints, statistics, cardinality estimation and other plan driven decisions is a waste of time. Since the majority of the performance difference is in that clustered index scan (1 sec vs. 28 seconds) it's likely to be a disk or memory problem. Although the actual insert operation is also twice as long. Same likely issue. - Grant Fritchey