Don't drive it until you fix it because this can damage the engine permanently.
The oil separator has failed. You need to replace it and the oil filler tube. When the separator fails, it pulls a huge vacuum from the oil filler tube and causes it to collapse. After the tube collapses several times it weakens and can crack. There is normally a vacuum on the oil filler tube, but not so strong it collapses, so you don't want any cracks or holes in that tube if it has weakened.
This same thing happened to mine last winter and it has been great since the fix.
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