This site seem have the most up to date numbers.
"Rejected absentee/mail-in ballots as a percentage of total absentee/mail-in ballots returned, 2016-2020"
The Reuters link specifically addresses that: it's a tabulation error, the older data shows ballots rejected for all causes, the 2020 data is limited to those rejected for signature mismatches only, they haven't released the all-cause number yet. And the signature rejection numbers broadly match up, both being sub-1%.