According to the research papers and professional groups I've looked as this is true. If you want to discount experts that are well aware of the problems, methodologies, etc., then I don't know how you'll reach any conclusion. Non-experts are rarely more accurate than experts on complex issues.
As to methodology, CDC lists and recommends methodologies for all diseases, and COVID deaths are counted by them using the same methodology that all deaths are, whether cancer, heart attack, car wreck, etc. So there is nothing special about how COVID deaths are counted from their recommendations.
Many states seems to have political pressure to downplay COVID, but I've not seen credible complaints (or any complaints) by whistleblowers claiming they're pressured to increase death counts.
And overall death counts versus expected death counts gives a picture of likely COVID caused deaths that makes them far undercounted.
I expect scientists to arrive at pretty good counts eventually, then political and nonsense spreaders to ignore anything that doesn't suit their narratives.
Here's [1] some CDC covid methodology info - if you google CDC COVID methodology or CDC disease methodology you'll find plenty of methodology on data collection.
[1] https://www.cdc.gov/coronavirus/2019-ncov/covid-data/covidvi...