Veldora's (Tensura) dragon form is limited;

Carsearin ended with destruction of dragons;

Volcanica (Re:Zero) has mental problems, got its body taken over by Aldebaran and now - according to a novel, has a high chance to be slain while not being a villain;

ASOIAF dragons are on brink of extinction;

A Good Bye, Dragon Life's plot;

Starting as the Black Dragon BOSS's main character stopped being a dragon around 33 chapters later;

Tomoe (Tsuki ga Michibiku Isekai Douchuu) is forced to not use her dragon form due to what happened after her fight against a main character.

We DO NOT need conditions, we need a proper (or better) dragon lore.