Yes, as you have seen there is now a limit on the number of columns that can be created for a list. This change first occurred in 14.1 where we changed the data representation of lists to hard tables in the database. Unfortunately, this has the side effect of limiting the number of columns in a list to the number of fields supported in a database table. When the limit is exceeded, the somewhat ungraceful postgres error is generated. My advice would be to normalize the list into multiple lists with fewer columns that could be joined together in a query on a key value.

Hope this helps,
Greg