Firstly, it's nonsense to take "average amount of deaths" over the past few years and extrapolate it to the current year without accounting for population growth changes, and rate of population growth acceleration.
Secondly, if you look at the "expected U.S. Death Rate" data[1], it shows that they expected U.S. death rates (per capita) to rapidly accelerate about 7 years ago, but the rate of deaths didn't really begin that acceleration cycle until ~2 years ago:
2017: 858.0 deaths per 100,000 predicted
2018: 868.5 deaths per 100,000 predicted
2019: 878.2 deaths per 100,000 predicted
2020: 888.0 deaths per 100,000 predicted
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2017: 731.9 actual deaths per 100,000 [2]
2018: 723.6 actual deaths per 100,000 [3]
2019: 867.8 actual deaths per 100,000 [4]
2020: Could be anywhere between 835-910 depending on the population data and total death numbers you use to calculate
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Not sure why people aren't dying as fast as they initially thought (probably modern medicine, etc), but that simply means there were more old people on the verge of dying coming into 2020. So even if 2020 shows a per-capita increase in deaths, it's to be expected.
[1] - https://www.macrotrends.net/countries/USA/united-states/deat... [2] - https://www.cdc.gov/nchs/data/nvsr/nvsr68/nvsr68_09-508.pdf [3] - https://www.kff.org/other/state-indicator/death-rate-per-100... [4] - https://www.cdc.gov/nchs/fastats/deaths.htm