This may depend on wether the size of the vessel is adequate for the overall system water volume. In many cases an additional vessel may need to be fitted in accordance with the boiler manufacturers advice. Often this not allowed for when going for the cheapest quote for a boiler replacement. It can also play a role in premature failure of a boiler. So yes it entirely feasible.

Hi the expansion vessel shouldn’t need re charging after 5 months it could be a faulty vessel , it should still be under a guarantee I’d like at replacing it under the warranty
This would explain why the system is losing pressure if it’s not the vessel there is definitely a leak on the system done where

You'll gain pressure on heating and lose pressure on contraction naturally during on off periods.
After installation, air from boiler and radiators relieved.
Expansion vessel factory set pre-charged from factory?
If needed to ADD more "AIR" there either isnt enough expansion to acomodate full power for ALL radiators.
Hope this helps

If you have a faulty pressure vessel then it won't be able to take the pressure rise when the boiler is on. The key indicator is that the pressure gauge will rise to 3 bar or above which will cause the pressure relief valve to open, you may notice water trickling from the pipe out side