The mass for BS3 supplied in pCondif (downloaded Feb 11th 2023), listed the linker mass as ~ 138, omitting two hydrogen atoms in the linker composition. In addition, the Mono composition includes the mass of an entire H2O molecule, although the hydrolysis of the Oxime ester would only an OH, as the second proton would dissociate.

Attached is a screen shot showing the corrected BS3 mass and composition boxed in green, and the incorrect Heavy BS3 mass and composition boxed in red. As you can see, the Linker composition includes only 10 protic species (H or D) instead of 12, in addition, the mono composition has the mass increase by 18, not 17.