The default sort order of mixed numbers & text is usually numbers, then text. Airtable seems to do symbols, alpha, then numbers.
For example, normally in in Excel stored as text:
1
18
1a
Airtable sorts as
1
1a
18
While not necessarily a bug (which is why I put it here instead of the other forum), it is not what is typical for other applications so it is inconvenient.