Yeh i have and also a lot worse than this. I am not sure on the exact maths but downswings like this should happen every X amount of hands.

Just part of the grind sadly but good to get it out of the way this early on in the year

It's really hard to say without looking at the hand history, but in theory swings like that could be caused by variance alone. It's obviously not super common nor super likely given how fast you lost those 10 buy-ins, but it can happen. As for the stop loss - it's more of a mindset thing than anything else. In theory, if you're correctly bankrolled there's no reason to ever stop playing, but human beings are not robots and even professional players with a great mindset can be affected by the loss of 11 buy-ins in a span of 2k hands. A quote by Tommy Angelo that I often like to repeat when talking about bankroll considerations like this (because it describes them so accurately) goes like this: "bankroll management is like buying mental insurance". Bankroll management is not a simple matter of risk of ruin or variance calculations, it's also about how losing affects you personally, and since it's so personality driven there's no such thing as "typical stop loss". Some people will feel comfortable with 10 buy-ins, others can benefit from taking a short break after just 3 buy-in loss, others yet will actually decrease their winnings by introducing any kind of stop loss. If I had to guess what's a good starting point for you I'd guess something in the neighborhood of 5-6 buy-in stop loss.

Before I opened the thread I already had the answer in my mind: it's probably a combo of both.

You ran bad and made a few bad calls, it's totally normal though, my graph after a long session used to look like yours quite often.