Less so than %, for example. It is classified as a sub-delim subset of reserved characters [1], meaning that they won't conflict with the generic URI components syntax and thus are reasonably safe. (* and $ are also included in this set.) You might be worrying that it gets "converted" into %2B but this conversion is not required and fully reversible.

[1] https://datatracker.ietf.org/doc/html/rfc3986#section-2.2