Hasn't that been covered a million times? Can't/couldn't/shouldn't speak publicly about ongoing investigations, etc. It's why it wasn't a thing in 2020 (except shitasses like Joe Rogan lying about it) because it a) legally could not be a thing, and b) Biden didn't need it in 2020 because he trounced Trump by over 7 million votes.
The same thing came up last year. The Maxwell trials and such meant, in their opinion, they couldn't use it. And they (this was the more public example) avoided using Trump's other ongoing trials, appeals, adjudicated rapes, and felony convictions.
Giving benefit of the doubt, it makes legal logic sense to do the above. "Protecting Clinton" only exists in the disabled minds of Republicans. I hope they've come to regret those choices. Yes, they may have seemed like the right thing to do legally at the time. But if you're certain that the other person is a dangerous fascist (and you have all the evidence to back it up) then it would've been better to bring those up in 2024 debates, speeches, interviews, and ads.
We can only hope there's a lesson learned. In 2028, and beyond, forever, use this stuff (all of it: Trump-Epstein, the crimes and the coverup, ICE, warmongering, rapes, trafficking, the drug cartel friends, 1/6, everything) against every single Republican who ever runs for anything, ever. Played nice, by the rules, and then the rules changed. It will happen again if it is allowed to happen again. After the 2028 there should be no coming back for the GOP.