The error is e.g.
Data too long for column 'custom_194' at row 1
Our values are 1 character so we set the DB Field Length to 1. However, this makes exports of this same field fail. It is exporting the label, not the value, so DB Field Length needs to accommodate the label.
Since this is unresolved https://lab.civicrm.org/dev/core/issues/181 is setting a longer DB Field Length my only alternative to letting exports work again?