Yahoo Finance error? Did the VUAA.L etf drop by 20% shortly after debut (May 2019)?

I’m learning more about stock indices and doing an evidence-based approach. Many sources tout Yahoo Finance as a great place to get stock market data, so I’m looking at its data for the Vanguard S&P 500 ETF listed on the LSE, the VUAA.L (in USD) as can be found on Yahoo Finance.

I’m just quite surprised to see that three days after its debut, the price plumetted from ~50 to ~39 USD:

Opening Price on Yahoo Finance:

May 16, 2019 39.43
May 15, 2019 50.30
May 14, 2019 50.00

Can this happen to newly launched ETFs? Or can this be a fluke with Yahoo Finance data?

Similarly, the latest data at the time of writing show a massive jump:

Mar 26, 2021 71.24
Mar 19, 2021 51.11
Mar 18, 2021 51.53

A similar ETF, VUAA.MI in Milan (Eur), didn’t have this same drop during May 14-16, 2019.

Can this be a data issue on Yahoo Finance? What can be done if you suspect some glitches in the data?

Or was this a fluke, related to liquidity issues for a newly-launched ETF?

Any insights would be much appreciated.