The phrase "despite being mostly" is grammatically correct and commonly used in written English.
It is typically used to introduce a clause that expresses a contrast or unexpected aspect of the situation described in the main clause. It can be used to express a variety of ideas, such as contradiction, surprise, or defiance. Example: Despite being mostly sunny, the weather suddenly turned stormy in the afternoon.
She's creating chances despite being mostly all alone up front.
Despite being mostly gas by bulk, it's more than 300 times the mass of Earth.
Despite being mostly at the development phase, CMCs have some very successful applications in several high technology fields.
Despite being mostly under-the-hood improvements, the new version of iOS does have some superficial changes.
Guerrero will be 26 next season and he is already considered to be one of the game's best players, despite being mostly surrounded by marginal players.
Australian Muslims who, despite being mostly born, raised and educated in Australia, still feel like their identity is being constantly questioned.
I'm a big fanatic for the well-presented book of reprints and I thoroughly enjoyed these comics despite them being mostly ridiculous.
Again, despite this being mostly a non-Muslim problem, government countering violent extremism programs seem to focus exclusively on Muslim communities while ignoring the hundreds of non-jihadist terrorists that actually kill more people than violent jihadists do.
In doing so, however, he further reduced the Democratic vote, and the state ended up supporting the election of President Grant, the Republican candidate, despite the population being mostly Democratic.
Unpublished quality improvement work undertaken at the study site has shown that billings and appointment availability went up post-EMR, despite the clinic being mostly closed to new patients, with the exception of prenatal and pediatric patients.
Mantle solidification and the drop in mantle heat flow occur slightly later for the inner model for two reasons: (1) the surface heat flow is lower than the other models in the first million years because the surface is hot, decreasing the upper mantle temperature jump; (2) tidal heating is initially moderate (∼0.1 TW) despite the mantle being mostly molten due to proximity to the star.
