Desk research against primary sources. Figures are traced to the issuing UAE authority and linked on the page.
The standard is really about coverage rather than any specific garment being banned outright: shoulders and knees covered reads as acceptable across almost any style of clothing, which is why an outfit fine on the street can still draw a polite request to cover up once inside if it drifts towards vest tops or very short hemlines. Staff apply the standard inconsistently between malls, so treat it as a floor to meet rather than a line to test.
Carrying a scarf solves the problem faster than arguing with mall security about the standard, and it is cheap enough to buy on the spot that there is little reason to plan an outfit change around it instead. Reserve swimwear entirely for the pool or beach areas within a hotel or resort — wearing it to walk between those areas and a mall is the specific version of this mistake that catches people out.