I have GoodTask on all three of my devices, my mac, iPhone, and iPad. The sync between iPad and iPhone is reliable, but it's horrendous with my mac (macOS Big Sur11.2.3 (20D91)). I tried all the fixes mentioned on this forum.
I understand that the reminders framework is the backbone of goodtask, but at this point, it's leaving goodtask almost unusable for me. I have noticed that the files in goodtask document folder update faster than it takes reminders to sync. Therefore I want to suggest "Goodtask list" that syncs via iCloud document storage, alongside the reminders list.