Hopefully this is what you're after.
See full flow below. I'll go into each of the actions.
Data contains your data.
Compose extracts the data out using the following expression. Effectively, it removes the brackets, then splits by semi-colon. If you knew that your brackets were always separated by a space, then semi-colon, then space, you could have just split on " ; " instead of just ";" which would remove the spaces, but assuming this might not always be the case so just splitting on the semi-colon.
split(replace(replace(outputs('Data'), '[', ''), ']', ''), ';')
Select is trimming your values (removing any unnecessary spaces at the start and end of your text. The expression used is:
trim(item())
This would give you the following output.
Join will then join each of the values in the array. In this example I've joined them by ", ".
This will give you the output below.
