diff --git a/src/yunohost/data_migrations/0021_migrate_to_bullseye.py b/src/yunohost/data_migrations/0021_migrate_to_bullseye.py
index 56044d48f..59b6ba517 100644
--- a/src/yunohost/data_migrations/0021_migrate_to_bullseye.py
+++ b/src/yunohost/data_migrations/0021_migrate_to_bullseye.py
@@ -35,6 +35,7 @@ VENV_REQUIREMENTS_SUFFIX = "_req.txt"
 VENV_IGNORE = "VENVNOREGEN"
 
 def _get_all_venvs(dir,level=0,maxlevel=2):
+    # Using os functions instead of glob, because glob doesn't support hidden folders, and we need recursion with a fixed depth
     result = []
     for file in os.listdir(dir):
         path = os.path.join(dir,file)