When installing plugins using plugin installer, permissions for new files are set to 666, and folders get 777.
This causes problem in some sites, as they don't allow PHP files with these permissions to be run.

I understand this is caused by some software in those servers, but it seems to be quite common, at least from what I have seen recently.

From the discussion here:
https://moodle.org/mod/forum/discuss.php?d=323867#p1329307

It seems that Moodle is using the same permissions to create files in data folder and in plugin installer.

I think it would be good to change this, or maybe set more restrictive default permissions, if that's a better option, I don't know.

Thanks,
Antonio