I just had a look through the diffs from 5.3 to 5.4. The fuse layer was heavily re-worked with 69 patches and this diffstat
fs/fuse/Kconfig | 11 ++
fs/fuse/Makefile | 2 +
fs/fuse/cuse.c | 101 ++++++-------
fs/fuse/dev.c | 656 +++++++++++++++++++++++++++++++++++++-----------------------------------------------
fs/fuse/dir.c | 299 +++++++++++++++++++++++----------------
fs/fuse/file.c | 1241 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-------------------------------------------------------------------------
fs/fuse/fuse_i.h | 361 +++++++++++++++++++++++------------------------
fs/fuse/inode.c | 561 +++++++++++++++++++++++++++++++++++++++++-------------------------------
fs/fuse/readdir.c | 72 ++++++----
fs/fuse/virtio_fs.c | 1252 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
fs/fuse/xattr.c | 76 +++++-----
11 files changed, 3035 insertions(+), 1597 deletions(-)
So it wouldn't surprise me if there was a regression there.
Looking at the changelog from 5.4 onwards I see some fixes for regressions introduced by those patches.
Is anyone brave enough to try v5.5-rc1 which should have those fixes?