Yes, the oceans will yield up CO2 if we start removing it. As CO2, it is a gas, and can dissolve into water to produce carbonic acid. Since the oceans are slightly basic (pH ca. 8.2), they can absorb a lot more CO2 than fresh water, which is typically near neutral (pH 7).
Formation of carbonic acid is shown as CO2 + H20 -> H2CO3 -> H+ + HCO3-. The proton from carbonic acid then drives pH down in the oceans. As long as the atmospheric CO2 is high, the carbonic acid formation will remain high, driving down the pH, which ultimately will cause problems for many species.
However, the above reactions are reversible, and the dominant form in the oceans depend on the amount of CO2 in the atmosphere. As you delete it from the air, the reaction shifts to the left, favoring formation of CO2. Since CO2 can out-gas from the water to increase pH to where we want it, removal of CO2 will reverse this trend.
But the problem is more dire than many realize. It is not just carbon generated by humans, but the warming planet has begun to release carbon from other sources. As the article in Nature below indicates, we probably need a miraculous invention for direct air capture and develop a means of sequestering the CO2. It does not appear there is sufficient land mass to grow enough biomass to compensate for the ever-increasing CO2 loading.
"Permafrost collapse is accelerating carbon release"
1.
https://www.nature.com/articles/d41586-019-01313-4