I don't know for certain that "Iconifying" is pinning, but I presume that is it. As WhyEssEff said, if you have quite a few tabs open you will need to scroll to see some of them, but pinned tabs are always shown as a small icon on the left.
I don't know how you are pinning tabs (if that is what is happening) on accident. It seems to me to be hard to do too.
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