High inflation
encourages spending. It is deflation that discourages spending. High inflation means that the money you have today will purchase less in the future, thus it pushes people to buy now rather than later when things will be more expensive in nominal terms. High inflation combined with low interest rates, will also increase financial speculation pretty much across the board.
The problem with high inflation is that it usually (but not recently) goes hand in hand with higher interest rates (i.e. money costs more). Which tends to discourage business borrowing, which acts as a damper on non-financial investment (i.e. spending on factories, marketing, R&D, etc.). This has the effect of slowing down economic growth.
On the other hand, high inflation/high interest rate environments tend to arise when growth is high. Because high growth tends to go hand in hand with a rise in wages, increases in demand (which shifts the demand curve, and thus raises prices), increases in financial speculation, etc.
There are a ton more "on the other hands". Economic analysis is complex and difficult because it's a tangled mess of interdependent feedback loops that constantly change. A single policy action has an avalanche of cascading effects, some of which will be counter to the policy objective. I'm not suggesting humanity should just roll over in the face of this challenge. We should just be aware that it's a "hard problem" and there are never any simple solutions.