In luatex 1.13.0 (texlive 2021) this here gives the wrong linkarea:
it stretches to the left from the end of the link instead to the
right. In texlive 2020 the behaviour is correct:


\pardir TRT \textdir TRT \linedir TRT

X
\pdfextension startlink
attr {/Border[0 0 1]}
user{
/Subtype/Link%
/A<<%
/Type/Action%
/S/URI%
/URI(blub)%
>>%
} Linktext
\pdfextension endlink
y

\bye