Sungold flavor deterioration

Is potash necessary to sweeten sungold?

When I picked the very first lone fruit that ripened last month or so on my sungold, the flavor was good. Slightly sweet with a slight tangy taste. Brix was about 8 if i remember correctly. About 2 weeks later and up to now, theyre almost bland. Ive planted it on a mound of bulk garden soil from a nursery. Just a couple of weeks ago, i added a 2" thick layer of mushroom manure on top.

The first batches of fruits were close to an inch in diameter when they ripened but they seem to be ripening earlier now at 3/4" diameter. Flavor is still not as good as the very first pick.

Is it necessary to use potash to sweeten it?