This will remove both the side-nav link and the mobile-tab link as well as redirect /tags to /all:
function classChanged(){
const url = self.location.href;
if (url === 'https://forum.example.com/tags') m.route.set('/all');
let tagLinks, i, j;
try {
tagLinks = document.body.querySelectorAll('*[href="/tags"]');
if(tagLinks != undefined || tagLinks != null)
for(i=0, j=tagLinks.length; i<j; i++)
tagLinks[i].href='/all';
}catch{}
try { document.getElementsByClassName("MobileTab")[0].getElementsByClassName("item-tags")[0].remove(); } catch {}
try { document.getElementsByClassName("sideNavContainer")[0].getElementsByClassName("item-tags")[0].remove(); } catch {}
}
let appF = document.getElementById("app"), ob = new MutationObserver(function(){classChanged();});
ob.observe(appF,{attributes: true, attributeFilter: ["class"]});