Isn’t a good practice open external links in the same tab.
Actually this is because technical limitation. ZeroNet running sites sandboxed iframe where the links with target=“_blank” does not work properly in every browser.
Probably related to https://www.jitbit.com/alexblog/256-targetblank—the-most-underestimated-vulnerability-ever/
When user clicks a link (that is modified for the code work), then the main receives this message with the link metadata, and then does the work.