I keep wondering about the lack of air power used by the Russians. Are their planes really that afraid of the Ukrainian anti-air defenses, are they really poorly maintained? Or is Putin holding back his air force in the case he needs it for WW3?
Yes
Russia's airforce is almost certainly gutted the same way their tank forces are (remember that they were supposed to have thousands of late-model T-72s in storage that turned out to be empty husks), and aircraft are more vulnerable to poor maintenance, have more valuable parts, and are made in much lower numbers.
Russia is demonstrably afraid of Ukranian air defenses. Even MANPADS* have inflicted a terrible cost on Russian fixed-wing aviation (including a number of aircraft that were able to get back to base after being hit, but will very clearly never fly again), and Ukraine's real SAMs have proven to be quite vicious (which will become even more true now that the first real Western SAM systems (based on the AIM-120 AMRAAM) are starting to arrive, which will vastly improve the ammunition supply) even if they've done more work shooting down terror missiles than planes. Russia has refused to operate heavy bombers in any capacity other than long-range missile yeeters, and most of the tactical air we've seen was flying extremely low to avoid attack (which is what made them vulnerable to MANPADS in the first place.
A fair portion of Russia's air forces are still stationed in Russia itself, in the increasingly laughable hope that they can stand against a NATO assault, and less absurdly to fend off any further Ukrainan air attacks.
BTW, Ukraine claims 268 destroyed Russian jets and it is one of the numbers I don't trust at all. Aircraft losses are highly visible and we would see the majority of those 268 visually confirmed (Oryx confirms 61 Russian combat jets lost... And 47 Ukrainian, our airforce is fighting heroically but in the end, their hardware is just too old)
Is the claim you're mentioning referring to aircraft destroyed or aircraft
shot down. Ukraine has launched a number of airfield deep strikes that almost certainly destroyed planes on the ground (including, possibly, as much as 20% of Russia's operational Tu-22M Backfire bombers), and those aren't in the Oryx data. Oryx data also wouldn't include the several strike craft that ate a MANPAD and flew home but were obviously a total loss.
*MANPAD = MAN Portable Air Defense - Stinger, Starstreak, Igla. An anti-aircraft missile carried by one soldier and fired like a bazooka.