I noticed this glow under Ledecestrescire when returning to the town recently and found that it was the spot for the crazy lady who demanded viper eggs. However, the lady is long gone as I had completed this quest months ago. Iām seeing this glitch/bug in TU 1.3.1 on my XBox Series X.
https://1drv.ms/v/s!AhFeScLdbsMBmH40ZakgnfG2uUPk?e=iEB1mX
Hello there @TheNorfolkian!
Thanks for taking the time to share this report with us regarding "The Stink-Brew" mystery, and for including a video which shows the lingering blue glow. I've passed this report along to the development team so they can take a closer look at why this glow is remaining after completing the quest.
If we require any additional information from you, we'll reach out within this thread. In the meantime, please keep an eye out within the News & Announcements forum for any future updates.
Thanks! 
devtrackers.gg