Brent Ozar looks at the “String or binary data would be truncated” improvement:
Don’t leave this trace flag enabled.
There’s at least one bug with it as of today on SQL Server 2017 CU13: table variables will throw errors saying their contents are being truncated even when no data is going into them. Andrew Pruski reports:
Special shout out to three of my co-workers on finding that issue. I had nothing to do with it but will take credit nonetheless.