I upgrade my version of Discourse yesterday & it broke on Brave (Ubuntu 20.04) with the following console error:
r.replaceAll is not a function
So I went through all the normal troubleshooting steps of turning off all of the plugins, turning off all browser extensions & doing a complete rebuild.
Even with all of the above I’m still getting a blank screen & the console error.
Today visiting https://meta.discourse.org/ using Brave desktop browser returns an identical error to my Discourse site:
jquery.js:4059 
Uncaught TypeError: r.replaceAll is not a function
    at ce (plugin-api.js:1788)
    at e.value (plugin-api.js:269)
    at onebox-decorators.js:48
    at e.withPluginApi (plugin-api.js:1756)
    at Object.initialize (onebox-decorators.js:47)
    at Object.i.initialize (app.js:46)
    at index.js:144
    at e.each (dag-map.js:231)
    at e.walk (dag-map.js:145)
    at e.each (dag-map.js:75)
    at e.topsort (dag-map.js:83)
    at n._runInitializer (index.js:158)
    at n.runInstanceInitializers (index.js:142)
    at n._bootSync (instance.js:110)
    at n.didBecomeReady (application.js:691)
    at t.invoke (backburner.js:371)
    at e.t.flush (backburner.js:263)
    at e.t.flush (backburner.js:470)
    at e.n._end (backburner.js:1044)
    at e.n.end (backburner.js:730)
    at e.n._run (backburner.js:1099)
    at e.n._join (backburner.js:1073)
    at e.n.join (backburner.js:790)
    at f (index.js:179)
    at HTMLDocument.<anonymous> (index.js:283)
    at u (jquery.js:3766)
    at c (jquery.js:3834)
Is anyone else experiencing this issue?