NFSV4 mount misplaces directory name, adding a comma ',' character trail to the name, resulting to an error. all related services run fine, there is no configuration issue here. When trying to mount there is an error related to the path!, path name is wrong on the error message. I use NFS on FreeBSD for decades. Sorry for saying that, but the sense of quality on FreeBSD kernel is gone. You are in a hurry to release new versions even if they are full of bugs. It is sad.
The directory path for an NFSv4 mount is different than for NFSv2, NFSv3, depending on what the server's configuration is. NFSv4 uses a single directory tree built up from all NFS exported file systems on the server. For the FreeBSD server, this is routed at the point specified by the "V4 ..." line in /etc/exports. For example: V4: / - Means that all mount paths are from the root of the server's file system tree. V4: /home - Means that all mount paths are relative to "/home". In this case: server:/ would mount /home on the server. "man nfsv4" and "man exports" should help clarify this. (Some say NFSv4 is NFS in name only.)