and in the newest version the line is the same but that rw turns to ro but I can see existing files.
ro is odd because storage is explicit mounted rw. LibreELEC-Generic.x86_64-13.0-nightly-20241206-ca4bded.img.gz has the kernel update 6.12 to 6.12.3. It include nfs commit 56a5d99 changing "something with ro". On my side it does continue working, but using NFS4.
These messages are normal, ignore them.
I can't specify disk=NFS4 as a kernel parameter
To mount a nfs4 server use e.g. disk=NFS=172.16.3.4:/mnt/media/storage,vers=4.2
As a test you may even try with disk=NFS=172.16.3.4:/mnt/media/storage,vers=3 to see if there is any issue in the LE parsing code.