It is caused by both because it’s essentially just a ratio between the two.

The money supply was increased by 45% in 2020. There is no way that this did not impact inflation

Interest rates do not affect inflation period, mainstream economics likes to push the theory that monetary policy is effective because frankly it is like the evangelical pastor claiming faith healing works. It is kind of fundamental to keep the whole circus going, but the empirical evidence is against it.

I like to point to Michael Roberts post on this issue. First I'd point out that inflation is being caused not only by the supply chain but also the skyrocketing corporate profits of the past 3 years. Also at the same time raising interest rates is not going to work unless the rates realy skyrocket over 3 or 4x the current value. Whatever you read in the MSM about inflation and interest rates you can pretty much ignore it.

As always I recommend the articles completely. Inflation: wages versus profits

Since the COVID slump, labour’s share of income and real wages have been falling sharply even as unemployment falls. This is the complete opposite of the Keynesian inflation theory and the so-called ‘iron law of wages’ proposed by Weston against Marx. The rise in inflation has not been driven by anything that looks like an overheating labour market—instead it has been driven by higher corporate profit margins and supply-chain bottlenecks. That means that central banks hiking interest rates to ‘cool down’ labour markets and reduce wage rises will have little effect on inflation and are more likely to cause stagnation in investment and consumption, thus provoking a slump.

The Economic Policy Institute reckons that, since the trough of the COVID-19 recession in the second quarter of 2020, overall prices in the producing sector of the US economy have risen at an annualised rate of 6.1%—a pronounced acceleration over the 1.8% price growth that characterized the pre-pandemic business cycle of 2007–2019. Over half of this increase (53.9%) can be attributed to fatter profit margins, with labour costs contributing less than 8% of this increase. This is not normal. From 1979 to 2019, profits only contributed about 11% to price growth and labour costs over 60%. Non labour inputs (raw materials and components) are also driving up prices more than usual in the current economic recovery.

and

The inflation debate

Central banks have little control over the ‘real economy’ in capitalist economies and that includes any inflation of prices in goods or services. For the 30 years of general price disinflation (where price rises slow or even deflate), central banks struggled to meet their usual 2% annual inflation target with their usual weapons of interest rates and monetary injections. And it will be the same story in trying this time to reduce inflation rates. As I have argued before, all the central banks were caught napping as inflation rates soared. And why was this? In general, because the capitalist mode of production does not move in a steady, harmonious and planned way but instead in a jerky, uneven and anarchic manner, of booms and slumps. But also, they misread the nature of the inflationary spiral, relying as they do on the incorrect theories of inflation.

The hardline monetarists call for sharp rises in interest rates to curb demand while the Keynesians worry about wage-push inflation as rising wages ‘force’ companies to raise prices. But inflation rates did not rise when central banks pumped trillions into the banking system to avoid a meltdown during the global financial crash of 2008-9 or during the COVID pandemic. All that money credit from ‘quantitative easing’ ended up as near-zero cost funding for financial and property speculation. ‘Inflation’ took place in stock and housing markets, not in the shops. What that means is that US Federal Reserve’s ‘pivot’ towards interest rate rises and reverse QE will not control inflation rates.

Dumbo here: why does increasing interests rates result in debt being harder to pay off? You mean debt accrued after the interest rates have risen?