An untagged trend block has a constant input, so it is useless. Because it has no tag, it really is little load on the system.
Trend block module 2,01,31 Block 22541 FC 66 is wired from constant block 5 (0.0)
See related message DBDOC-CHECK_CONSTANT_TREND_TAG.ERR
Note also: Error messages can be built directly into your M14 file. For more information, see Building error reports into the M14.