What is the problem?

That thing looks fried. i'd wager the 'professional' stuff is quite hot. Doesn't take long for a tap root to grew a few inches beyond whatever hole you filled in with seedmix. Plus, when you water, it's notlike it stays mutually exclusive.. the liquid will mix the concentrations along boundary with the "pro" stuff etc... start in a seedling pot with the seedmix next time. You can wait this one out if you want, but if it's an auto i'd just restart. Even as a photo, i'd probably restart, too, but let this grow on the side to learn and if it keeps up so be it, just gravy on top. Potting up should never stall a plant. It actually promots a better rootball compared to starting in a large, final pot. Even for autoflowers. That's not a popular statement, but it's true. If you shock an autoflower just be potting up, should look into a new hobby. it's a bit mind-racking to start, but no worries... keep it simple to start, the slowly add layers of sophistication... that way you can easily revert when something is bullshit, and you will run into a ton of bullshit. Do too many new things at once and you never know what was responsible for any improvements you saw. Genetic variety is a thick fog of war on its own.