I have noticed for a while now that listing prices just change by themselves. I always have round numbers, but the random changes are easily spotted as they have parts of euros eg 48,60€ and not 48€ or 49€. Unfortunately, as my items are usually one of a kind, I can't always remember what I priced them at, so is Etsy going up or down with their altered prices. Every few days I have to change prices back to the nearest round number. This site is riddled with bugs, some annoying and some very serious.
Prices show with any VAT/GST applicable in the buyer's location. Etsy collects and remits the VAT, you will get the price you listed at, less fees.
I know how the prices/VAT shown works and that is not the issue....Just SOME random items are affected and not always the same ones. I am looking at my own listings in my shop pages, whilst logged in, or in my shop manager listings, and just odd ones have had their prices changed.