Hello Enterprise206 - I'm going to take a couple stabs.
1. The power thing. Sounds like maybe some trash from the gas tank got sucked into the carb, and clogged in the main jet maybe. Or, check the airbox. Maybe something is sucked up against the filter, or in some way, the air coming in has gotten blocked. At low air demand, no problem. At high air demand, the blockage is not allowing enough air. Just a stab.
I think if the clutch were slipping you'd be saying something like, when at full throttle in 4th, the revs climb higher than the bike speeds up … or the revs climb freely, but without much acceleration. Something like that. But, I've been wrong before (every day).
2. The ticking thing. Left side only. Could it be something with the chain and/or sprockets? One spot in the chain is causing a noise when it contacts the front sprocket? I dunno. Like I said, just spit-balling.
BTW - I'm maybe an hour west of you. I'm in Peachtree City, GA.
2016 Honda Rebel 250 - The "Piglet."
AFR sensor equipped and downsized to a 0.105" main jet.
The only changes so far.
Bought on 6/29/19 with 44 miles.