Those add up to about 20%. That's 20% of Republicans who showed up to a primary to vote for people who aren't even running anymore. That's a protest vote. There's a significant number of Republican voters signaling that they're not going to vote for Trump no matter what.
They'll vote Republican straight down the ballot, except for the guy at the top. They may or may not vote for Biden. But they're not checking off Trump on the ballot.
And that's exactly how Trump lost states like Georgia in 2020. In 2020, 11,000+ Georgian Republicans showed up, voted Republican but left the Presidential spot blank.
It's going to happen again.