Comparison of abundances between our four targets and other young stellar objects. The panels from left to right show the abundance ratios with respect to methanol based on CH₃¹⁸OH, ¹³CH₃OH, and CH₃OH. The sources considered to be or that have been in outburst (L1551 IRS 5 North, Haro 5a IRS, V346 Nor, OO Ser, VLA4A/B, HOPS 373SW, V883 Ori) are slightly shifted to the right, while the quiescent sources are shifted to the left. In the case of B335 we plotted two epochs, one from 2014 representing the quiescent state and another from 2016 when the source was bursting. We consider the abundance ratios calculated with respect to the main isotopolog of CH3OH as upper limits.