I’d prob say your digestive absorption issues are most likely why it’s low- so that would be the cause, not a symptom of deficiency- esp if you’ve had a flare in these recently causing it to drop from your previous test dates.
Folate is needed for so many important functions and could def be linked to your other symptoms so worth doing something to stop it getting to the point of deficiency and see if your symptoms get better.
for deficiency to be flagged by your GP/lab, it would usually need to be below 3ug/L depending where you are in the country, (although optimally some would argue should be higher and certainly should be if planning any pregnancies) if deficient there would likely be other indications of abnormal b12 and red blood count also, so not something your GP would automatically address just on this result alone.
given your symptoms you could ask for further testing on NHS but not likely to get it as the symptoms are slightly non-descript and could apply to a lot of things (although sore tongue - glossitis?? Slightly more specific) when clinically you are only borderline. Further investigations could include things like homocysteine (a protein that would be high in true deficiency) red cell folate (how much is actually in your blood cells rather than just carried in serum) active holotranscobalamin (a form of b12) and assume they have already carried out full blood count? Otherwise you can pay privately for these things if you want to know/rule out it further for your own peace of mind.
And /or suggest you talk to your dr about wanting to supplement- esp given your digestive issues and likely malabsorption would be a good idea, and if agreed then look for a methyl vitamin B complex to buy (methyl forms are easier for the body to utilise) and see if your symptoms ease up in a few weeks/months. Your dr can prescribe high dose of folic acid but you really need to make sure you stock up on all your b’s as there can be a knock on effect on these.