FWHM values before and after the 2015 fiber change (marked with a black dashed line) for the 5 stars in this paper. The red points are the final FWHM values after considering the focus drift correction which only affect the data pre-2015. The horizontal blue dashed lines mark the median values before and after fiber change to calculate the observed FWHM offset. The bottom-right plot shows the FWHM offset (which is positive for most of the stars) for all the stars in our sample with more than 5 observations before and after the fiber change.