This

#include <TFile.h>
#include <TROOT.h>

void foo() {
   // works
   auto *f2 = TFile::Open("~/Scratchpad/work/UnROOT_RDataFrame_MiniBenchmark/Run2012BC_DoubleMuParked_Muons.root", "READ_WITHOUT_GLOBALREGISTRATION");
   gROOT->GetListOfFiles()->Print();

   // doesn't work
   auto *f = TFile::Open("root://eospublic.cern.ch//eos/opendata/cms/derived-data/AOD2NanoAODOutreachTool/Run2012BC_DoubleMuParked_Muons.root", "READ_WITHOUT_GLOBALREGISTRATION");
   gROOT->GetListOfFiles()->Print();
}

yields

Processing foo.cpp...
Collection name='Files', class='TList', size=0 // OK
Collection name='Files', class='TList', size=1 // KO
 TFile: name=root://eospublic.cern.ch//eos/opendata/cms/derived-data/AOD2NanoAODOutreachTool/Run2012BC_DoubleMuParked_Muons.root, title=, option=READ

i.e. the READ_WITHOUT_GLOBALREGISTRATION is ignored when using TFile::Open to read a file via xrootd.

This might lead to unexpected performance degradation as well as use-after-deletes in some cases (e.g. a TChain with kWithoutGlobalRegistration uses TFile::Open to read a remote file, loads a tree (which will have the kMustCleanup bit reset by the TChain), then if the global list of files is cleaned before the TChain is destroyed the chain will have a dangling pointer to its fFile and fTree).

This is likely not just an issue with xrootd files but all TFile implementations except the local.