This is normal. Someone bought at your asking price, so you (and the buyer) moved the price of this relatively seldom traded ETF after days of no trade. Sometimes such ETFs jump 5% simply because there hasn’t been a trade for weeks. If it’s more liquid, you move the price after a few minutes or seconds, but essentially the same.
Before you buy another ETF, I recommend you go to Swissquote and search for the ETF in the market u want to buy at. Click on the price graphs and 2 graphs will open, price & volume.
In the attachment you can see it for last week for HSPX.
There’s your two trades of 55 shares (right?) on 15th and 20th.
Like @nabalzbhf also already mentioned, If this is what the trading volumes look like, I avoid the ETF, or at least the ETF at this market.
Who bought your 55 shares, maybe it was the market maker, maybe not, but probably it was a bit below the market value, so a market maker algo decided it was worth it, based on the futures for today’s opening.
And it’s usually better to trade ETF’s of US shares when the US market is open, it’ll reduce the spread.