Iran has (had?) S300 and maybe S400 yet downed no F35s despite many months of them in their airspace. I'm not suggesting US stealth makes the planes invulnerable but the evidence we have so far does not support your statement.
These are not 'point systems' with 'A on B' capabilities aka 'it works on this but not that'.
They are networked systems that work in the context of a layered AA strategy along with many other parts.
A single S300 system outside the context of a layered strategy is useless and will be picked off quickly.
We have ballpark estimations for their capabilities, and S400, in proper defensive posture, will hold out against anything NATO has ... for a while.
(Not accounting for 'magic' unknown gear that either side has)
AA defence will have long range radar, AWACS, satellite, other point systems, all kinds of EW (electronic warfare), and defensive patrols of various kinds. And we're now seeing Chinese passive systems deployed in Iran as well.
If that layered defence is very effectively managed, then it becomes very hard to pin the various pieces down. SEED munitions are maybe 60 miles range, and S400 can see F35's at 50 miles, that's a 'very tight' standoff even in a theoretical situation. If an adversary has AWACS then they're not going to use their tracking radars so the F35 has nothing to launch at.
There are all sorts of things adversaries can do to spook NATO AWACS off, push them back, which shortens the distance at which sorties can take place.
If a nation has 'all the layers' and they have good leadership, training, and are nimble and know what they are doing, they can be effective.
If there is 'kink in the armour' or the defence is piecemeal, it can be picked apart.
Think of it like those Roman Phalanx: we can't just say 'they have a certain shaped shield' - it's everything together. Coordination, training, tactics makes them hard to penetrate, but incompetence, exposed flank, etc. and they will break.
Also, Patriot is more capable, but given 'apparent doctrine' of limited munitions, the West has badly depleted inventories. Russia is pumping out enormous volumes of supplies. All of that means they get used differently.