Steel Track Frame stiffness

just noticed that the whole bb area kind of slightly flexes / bents (?) when pushing hard like starting from a traffic light with low rpm´s and quite heavy forces on pedals .

theres no damage to the lugs, no dents, cracks or whatever

apart from that, the frame feels stiff and good and rides very well.

has anyone had similar experiences?

i thought that maybe these frames are not really made for pedaling hard at low turns as on track you likely accelerate hard from higher speeds as from standstill ..

gear ratio is 42/16 which is quite short but lots of hills around my town.

All bike frames flex. You've just noticed it for the first time.