For me it's been much better lately. It now auto syncs within 10 to 15 seconds after opening the app. However, I completely stopped using the Evernote tasks feature because, even if the app syncs fast when I open it, it doesn't sync in the background even though I activated background refresh in iOS settings.
I did the test, I created a task named TEST on my Mac and set a reminder for 1 hour later. I made sure not to open the app on my phone, and even 2 hours later, the notification had not appeared on my phone. Sure enough, I then opened the app and 10 seconds later, the TEST task appeared, but I did not get the notification.
I did the same test with Things 3, my task manager of choice, and background sync was fast and seamless and I got the notification. For my notes, it doesn't matter, but for tasks, this is kind of a dealbreaker for me as the notifications are not reliable and I missed quite a few reminders because I didn't think to manually refresh by opening the app after creating them on my Mac.