Where is the correct ruling regarding depositing money in a conventional bank with variable interest, after realizing the prohibition of usurious interest?

Usury (Riba) is one of the gravest sins after polytheism (shirk) and killing a soul. Those who engage in it are cursed, and its lowest degree is like a man having intercourse with his own mother. It is not permissible for a Muslim to deal with usurious banks or deposit money in them, because it constitutes aiding in sin. However, if one is compelled to deposit money due to the absence of an Islamic bank and fears the loss of their wealth, or to receive their entitlements, they may open a current account without interest. If interest is obligatory, they should take it and spend it on the welfare of Muslims to dispose of it, not as charity. What you have done is correct, and you should advise others. Fatwas permitting this may be intended only for situations of necessity.