There is an inherent tradeoff when using small speedlights outdoors in daylight. They are light, and convenient and cheap. But they don't have a ton of power.
And the aggravating factor is the relationship between a small flash and a bright environment. Which is, in turn, governed by our sync speed. And by this I mean our natural speed limit for flash, absent power-robbing gimmicks like high-speed sync (HSS).
At a sync speed of 1/250th of a second, even at a low ISO, you are probably going to be at f/16 in full sun. That's a small aperture, which means your flash will be working hard to create a full exposure.
Because of that, working in full sun with speedlights usually means we lack the power that we need. Certainly, we don't have enough power to push the flash's light through a softening modifier to look nice.