T233963: Add serialization options to RESTBagOStuff added a serialization type parameter to RESTBagOStuff with possible values:
The purpose of the "legacy" serialization type was to give any RESTBagOStuff users the opportunity to migrate to one of the other types. This was done in an abundance of caution, as there were no known users, but it is possible that third party private wikis were using RESTBagOStuff.
The "legacy" type was marked as deprecated in 1.34, with a comment that it would be removed in 1.35.
After the 1.34 release, remove the "legacy" serialization type, so that it will not be present in 1.35.