Again proving an old adage that you can't just give someone good weaponry and expect them to win based on the innate capability of those weapons alone.
Its like giving Iraqis an M1 Abrams - they run a single tank down a tight urban canyon of 4-5 story buildings, manage to perch it up on a smashed Renault truck and a concrete fountain, watch it get dogged by a group of teenagers throwing makeshift IEDs down from open windows, then complain about its 'inferiority.'
Reminds me of Korea and Viet Nam where its very obvious who were the pilots flying MiGs that achieved high kill ratios in A2A combat; it wasn't the natives.
I believe the VCs managed to have several kills on their own in the 1970s, because they had equally good equipment (Mig21s vs F4s), had several years of training in the USSR, had built up lots of experience flying, and had superior tactics that well adapted to the USAF mission profiles and the capabilities of their Migs. They would "boom and zoom" loaded F4s and F105s on bombing missions. That was partly due to poor tactics from the USAF, who dismissed dogfighting as outdated, and whose Phantoms didn't even have cannons early on*. The VCs were good at exploiting this tactical shortfall, until the USAF pivoted to US Navy old school dogfighting tactics.
*Interestingly enough, the F35 newer B and C variants don't have cannons either, then again they might be safer without ....
The F-35's 25 mm cannon can fire over 3,000 rounds a minute. The military is still investigating what went wrong with this one round.