Error loading tag list

Guys, before saving to the Firebase database, I check if the item has already been saved. Before, when there was just the Subgroups Tag, it was easy. As I now use the Firebase Authentication UserId together with the Subgroups Tag, I don’t know how to identify duplicity.
Follow the blocks and their explanations:

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Registration block.
First I check if he selected the group (A, B, C, D and E).
Then I check if the subgroup is already in the list. If so, I inform you that the chosen subgroup is already registered and I ask that another one be created.
If there is no Tag in Firebase, it is the Firebase Authentication UserId and the chosen subgroup.

At the bank it looked like this:

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Can someone help me?

Hope this will work !
Screenshot (37)

I did as you said but I used my variable and look what it shows.

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Guys, can anyone help me? Please?

Your value was a list, so if you add a list as item into another list, you get a list of lists

Taifun
PS: you forgot to tell us, what you want instead

When in the bank it was recorded like this:

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I validated whether the information was within the list. If so, it would pass information to the user that the item had already been recorded and that he or she could choose another one.

As I am now using the Firebase authenticator UseID in the same tag, I cannot perform this validation. If you do this, the UserID appears.

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I want to get this second layer which is the list of subgroups

Did you want to get sub group value ?