It could be because as reported in Apache Docs:
AllowEncodedSlashes Determines whether encoded path separators in URLs are allowed to be passedthrough
With the value NoDecode, such URLs are accepted, but encoded slashes are not decoded but left in their encoded state.
If Collabora expect path passed thru as encoded it could break collabora functionality. In the setup guide of collabora is specified to set that parameter as NoDecode. (have a look to: Collabora Online Development Edition (CODE) - Collabora Office and Collabora Online )
PS: Apache guide also specify that if encoded slashes are needed in path info, use of NoDecode is strongly recommended as a security measure. Allowing slashes to be decoded could potentially allow unsafe paths.