People tend to invest in risk-off US securities (stocks, bonds, etc) when there's more risk in the markets (inflation rises, economies cooling down, pandemic) because the US is THE financial superpower of the world and is almost guaranteed to keep your money safe, especially in treasuries aka US government debt because you can trust the US to pay the interest on its debt 150% of the time.
So bonds get issued for let's $100, and the interest rate on that is 5%, which will get paid in 10 years, you buy it, and in 10 years, you'll receive $5.
When someone wants to buy that bond, demand increases, so the price of the bond itself increases and it goes to $110, but you'll still receive $5 at the end of the line and that means the yield on it decreases to 4,5454..%, because 5/110 < 5/100.
This works the other way around as well. It demand drops, so the price of the bond drops to $90, and the yield is 5,55%.
So the surprising thing in the graph is that treasuries usually go in tandem with the dollar, because people flock to it in times of stress and buy things in other currencies when there's little stress. Now, though, the dollar is dropping, but yields are staying at the same level, maybe even somewhat elevated, which indicates that people, institutions, etc. are selling dollar assets, and thus, the yield stays the same even though the market might be rising.
This is worrying because, as we saw yesterday, when the market pumps, people STILL sell treasuries to buy equities and that means yields might keep rising even though the stock market is up as well, which in turn will be a shit sandwich for Scotty B when he has to refinance 7 trillion dollars in debt this summer. (He prefers to get the 10y below 4% and the 30y below 4,5%)