One common problem with the 5 gallon Buckets, unless a perfect aerated mix or uppotting practices or thorough understanding/ experience with a specific medium is this~
Roots swirl around outside of pot because that is the optimal aeration - especially being a young plant in a huge pot. The plant won't need food for at least 1 week per gallon of soil
Then when they thrive they drink too fast and you see those main roots outside the pot die off because they are on the outside of the pot and cause random issues.
After learning this from an old member here uncle ben who talked about plant moisture stress symptoms and solutions, it helped me plan against that. Everyone's environments and soils is different depending on where you live and your experience with the medium. With that being said I choose fabric pots or plastic air pots to make sure roots don't swirl around the outside of my pots.
As well as spinout being a possible issue, if the salinity is high in the medium and it get too dry you may see issues that aren't actually there just due to the water being gone and the salts in the media being stronger and frying the roots