@Lorence
No idea, but you could test to see if it's a timcycle modifier in any of the 'timecycle_mods_1>4.xml' files.
Download
this.
Use
WinRAR to extract files.
Backup 'update.rpf'.
Install all 4 'timecycle_mods_1>4.xml' files here:
...\mods\update\update.rpf\common\data\timecycle
Test in-game & see if effect is removed.
If the effect is gone, test out one file at a time until you figure out which one the timecycle modifier resides in, & then by blanking single or blocks of timecycle modifiers in that file (overwrite parts of your normal 'timecycle_mods_#.xml' file with data from the linked ones above) , figure out which one it is.