I’ve reported this issue on the backstage, as despite my guess, I see app Help does state
If linkType is not supplied, unlink actions will remove links of all link types.
…although clearly this is not the case. Fortunately, we have a workaround pro tem.
As to basic vs text links, at present the process does both. Perhaps make a feature request that unlinking operators have an optional third parameter with values ‘basic’, ‘text’ or blank. If the latter the current behaviour of deleting both basic and text links will apply.
For my own part I generally use these functions only for basic linking (and for notes generally lacking $Text, or text links) and I’d overlooked unintentional blow-back by unlinking removing text links. This also shows a disparity in scope of action between
link which only ever creates basic links and
unlink which potentially removes all links - both basic and text.