Hello and welcome.
You could always buy a silicone (Silikon) rubber bung if it concerns you. Otherwise just ensure that you proceed with whatever purpose without inverting the flask.
Wine bottles will be at risk of breakage if subjected to heating, whereas borosilicate flasks are more resistant both to thermal shock and caustic alkalies. The latter can still cause damage over prolonged periods, however.
Without a bung, your flask will be a case of "stirred, not shaken"
“There is a way of manipulating matter and energy so as to produce what modern scientists call 'a field of force'. The field acts on the observer and puts him in a privileged position vis-à-vis the universe. From this position he has access to the realities which are ordinarily hidden from us by time and space, matter and energy. This is what we call the Great Work."
― Jacques Bergier, quoting Fulcanelli