The Barilla website says that different areas use different wheat at different times:
"Where is Barilla pasta made — in the United States or Italy?
Barilla Pasta that is sold in the United States is made in our plants in Ames, IA and Avon, NY, with a few exceptions. Barilla Tortellini and Barilla Oven Ready Lasagne are made in Italy. Our Barilla Italy products state "Product of Italy, Distributed by Barilla America, Inc." on the packaging. We also have product that is made in Canada. Barilla opened the Ames plant in 1998 and our Avon plant in 2007. The Barilla family was very concerned about maintaining Barilla's high quality standards in the new plant. Consequently, the machines used in our Ames and Avon plants are the same as used in our plant in Parma, Italy. The recipe and the wheat blend are the same as that used in Parma, Italy. Barilla purchases its wheat from around the world, ending up with the best wheat available.".
Wikipedia: Barilla:
"... The company markets pasta in the US as being Italian ("An Italian Favorite" marketing) in flavor, but most of the product in the United States is actually made in Iowa or New York and not Italy. The wheat used is mainly local.
Barilla Group has several production plants all over the world: in Italy, Greece, France, Germany, Norway, Russia, Sweden, Turkey, the United States (in Ames, Iowa and Avon, New York), and Mexico. The company also operates mills in Italy, Greece, Sweden, Turkey, and the US. While its central office is in Parma, it has corporate offices in several other countries as well, such as Austria, Belgium, France, Germany, Greece, the Netherlands, Poland, Russia, Slovenia, Sweden, Switzerland, Turkey, the US, Mexico, Brazil, Australia, and Japan. Barilla's Italian production facilities are located at Parma, Foggia, Marcianise, Castiglione delle Stiviere, Cremona, Melfi, Rubbiano, Novara, and Ascoli Piceno. Its plant in Greece (near Thiva) is the third largest in Europe. The plant where the pasta was made is noted on the packaging by a code letter, whereas products made in Italy are explicitly labeled as such. The wheat used to make the final product is purchased from around the world.
The recipe was changed in 2016, and is occasionally updated:
"The company continues to improve the nutritional profile of its products, replacing palm oil in its bakery portfolio and expanding the range of whole grain products.
The new Bio/Organic Pasta is launched on the European and US markets: 100% selected durum wheat from organic farms.".
Grain grown in different fields is transported via various routes to different markets by different train and trucking companies; all wheat isn't identical.
Click to zoom in on central USA
Different countries have different regulations concerning the production of pasta, and there are different species of cultivated wheat. Durum wheat is usually used for pasta, it is ground for its wheat middlings and used to make semolina.
Barilla also changed its source of wheat due to concerns over glyphosate pesticides and contamination from Bayer Monsanto's RoundUp wheat.
That provides a few sources explaining why it tastes different depending on time and place.