Hello again,
GTF's very rarely dig and your situation doesn't sound like brumation. Young frogs will almost never brumate, even adult frogs in captivity virtually never brumate unless their keeper is specifically trying to trigger it. Rather the issue you are experiencing is more likely to be related to a few things such as illness, stress or your husbandry.
Does your frog have plenty of hiding spaces? If your frog is experiencing stress due to a lack of ability to properly hide itself in it's new enclosure, it may be driven to try and bury itself. This is especially seen when frogs are kept in a high traffic area in the house with few hiding spaces.
Does your frog have a bowl of water that they're able to properly submerse themselves in? If they're skin looking moist and sticky? Dehydration can cause frogs to go to ground to try and absorb the moisture in the soil. Misting can also help if your frog is too nervous to soak.
What are your temperatures like? If your frog is too hot, it may be going to ground to try and cool itself off.
Otherwise, if all of your husbandry is correct, you may wish to take them to the vet for some cultures to see if there is an underlying issue that is making your frog feel unwell.
Also, quick note: Is this the same frog that was showing the patches/spots of discolouration from your other thread? Is it still demonstrating these symptoms?