What changes at 60% fluency? I am now hitting a brick wall on progress in both Spanish & German. ??
Fluency on Duolingo is borderline meaningless, however, they do accept that there's no way Duolingo could get you to fluency on its own, so it doesn't go up to 100%. If you're around 60% fluent according to Duolingo, that's about as high as it's going to go. Longer courses go a little higher, shorter go a little lower, but somewhere around 60% is where they max out.
Assuming you have finished the courses, you're now in territory where gilding the tree is an option, if that feels useful, or where you can do reverse trees/laddering, or where you might have exhausted what Duolingo has to teach you and need to find resources for those languages elsewhere. It's impossible to guess merely from a fluency statistic and levels.
Nothing changes really. You'll probably just go up again at a random moment. After completing the tree in the first five months, I reached 63% fluency after doing about 50 xp per day for 15 months total, and that didn't budge for the three months that followed. Now I've done almost 24 months at a total average down to 40 xp per day, and a month or two ago "fluency" suddenly jumped up to 67-68%. I'm 850 xp from reaching the last level, Level 25 (30,000 xp), and have not read of any fluency mark in German above 68% so I suppose that's where I'll stay. Don't be too concerned, you'll feel fluency (or lack thereof) when you converse in German, and Duolingo, though very helpful, doesn't bring you there. Only talking in full sentences and interaction with others will confirm your proficiency.