"Disproportionate effect" means that something has a much bigger impact or consequence compared to what would be expected or considered fair. It suggests that the effect is not in proportion to the cause or the situation. Full definition
If a company has high operating leverage, and sales decline, it can have a shockingly disproportionate effect on the net income of the firm. (thebalance.com)
· Disproportionate effect of relatively few active employees on the many in the bargaining unit.This is particularly the case when collective bargaining involves a system - wide structure of elections, or when an earlier workforce voted the union in and the current one doesn't want it. (californiapolicycenter.org)
That's because cities are, by their nature, prone to disproportionate effects from destructive weather phenomenon such as heat - waves or tidal surges. (earthtimes.org)