You should use archive.org or archive.today links.
The best way to influence the Domain Authority metric is to improve your site’s overall SEO health, with a particular focus on the quality and quantity of external links pointing to your site.
You can use the Wayback machine addon to easily get archived links https://addons.mozilla.org/en-US/firefox/addon/wayback-machine_new/.
And a bookmarklet for archive.today:
javascript:void(open('https://archive.today/?run=1&url='+encodeURIComponent(document.location)))
FYI, if you’re worried about archive.today going down and references being lost, you can manually leave in the original URL by adding https://archive.ph/o/ in front of any URL, after you archive it. IE: https://archive.ph/o/https://sh.itjust.works/post/26060585 will redirect to the archived page, if it exists.
any link someone posts to Lemmy should be assumed spam until proven otherwise. Even if it isn't today, the protocol is open and so there are lots of options for spammers to automate everything about generated an account and then posting links. So far Lemmy isn't popular enough that much effort has been put into it, but there is still a lot of spam moderators have to remove. Links to reddit are a good place to obfuscate things - just create a reddit group for your spam, then post stuff there all the time, and link to that - there are extra steps but you save hosting and appear more legitimate to those who don't realize what is going on (until someone removes you of course, but then repeat with a different group)