Performance issues since migrating from SQL Server 2012R2 to 2019

I’ve migrated my database from a SQL Server 2012R2 to a new SQL Server 2019. I’ve just backupped the database and restored it on new sql server. After that I’ve imported and updated some additional data (quotes) with IMPORT, INSERT, UPDATE or MERGE. And in between some testers have used the system for some testing. Now performance is on some actions slower than on old server.

  1. First I’ve done some index tuning. Here are some questions regarding this topic:

    Questions on updating statistics and index maintenance jobs

    Index and statistics optimization scripts duration and log bloat problem. Looking for good strategy? (closed)

  2. Second I’ve done the same import done on our test environemnt with SQL Server 2012R2. And there I don’t have the performance issue.

Execution plan on Server 2012R2:
2012R2 Execution plan

Execution plan on Server 2019:
2019 Execution plan