I've been using it without problems for many years. About 3-4 months ago, scripts started to be deleted when syncing, I was shocked! I added several accounts to save the scripts, and noticed that after a while many of the scripts disappeared.
It's good that I had a backup, because I have almost 200 scripts (but half are disabled now). And so it would be... It would be a disaster to lose everything over the years. In short, after synchronization, the program deleted most of the scripts and left 20-30 pieces. I figured out how to delete the sync and saved it manually.
Now, about 2 months ago, new problems started. Scripts stopped working on different sites, from YouTube to others. And most importantly, you don't even think about it. I noticed that the functionality on YouTube is missing. And only then did I notice that the script manager had fallen off there and was no longer working on YouTube, the icon was not glowing on YouTube.
Now new problems have begun. And I also didn't think about the script manager, but I thought about the scripts themselves, that they didn't work. But it turned out to be him.
I turned on Tampermonkey and everything worked. Before the latest updates, everything worked fine for years, so you don't even think about the script manager.