freebsd stable - Dec 2017 - New in 11? ZFS ACL -> aclinherit stacks synthesized mode ACEs

Hello,

quick question, haven't had time to investigate yet, but accidentally
noticed that something between FreeBSD 10 and 11 has changed regarding
ZFS ACL inheritance.
Example:
If a parent directory has the file-inherit flag is set in a mode
synthesized ACE, the ACL of a file in that directory get the mode ACEs
stacked:

getfacl DIR
# file: DIR/                                                           
# owner: toor                                   
# group: wheel                                  
            owner@:rwxp-daARWcCos:fd-----:allow
            group@:rwxp--a-R-c--s:fd-----:allow                    
         everyone@:----D---------:-d-----:deny                           
         everyone@:------a-R-c--s:fd-----:allow

touch DIR/testfile
getfact DIR/testfile

# file: DIR/testfile      
# owner: toor                                
# group: wheel                                        
            owner@:rw-p-daARWcCos:------I:allow   
            group@:rw-p--a-R-c--s:------I:allow       
         everyone@:------a-R-c--s:------I:allow
            owner@:rw-p--aARWcCos:-------:allow
            group@:rw-p--a-R-c--s:-------:allow
         everyone@:------a-R-c--s:-------:allow

The (my) ACL of the parent hasn't change for some years (and aclinherit
is set to "passthrough-x" and aclmode is "passthrough", also
unchanged
for several years).
I never saw the resulting ACL before FreeBSD 11.1

Anyone out there who knows what changed why?

Thanks,

-harry