I mean it’s easier to build something new than guess how a black box you don’t have access to works (short of spying on the manufacturing facility). I’m sure Russian missile technology has at least somewhat kept up.
I watch combat videos daily and Iskander is easily their most potent weapon after Lancet drones (and artillery). Patriot can't cover the whole massive frontlines.
The most potent weapon in their arsenal right now in terms of battlefield value are their helicopters and glide bombs
Ukraine is hitting Russian air defenses with ATACMS, successfully and repeatedly. Corresponding attempts with Iskanders and Kinzhals to target the Patriots have largely failed.
There seems to be a wide gap in capability between the two scenarios - in either the attacking missiles, the defending systems, or both. Ukraine doesn't have enough Patriots to defend everywhere, but they're dramatically more effective than the Russian equivalents where they are stationed.
If nothing else, the war has been a huge advertising boon for Western defense contractors.
> There seems to be a wide gap in capability between the two scenario
This is entirely premised on Russian air defense being equal in high value areas vs Ballistic missiles (which is easily the hardest test, even for the US). Patriot systems were tested many times IRL against SCUD missiles during Desert storm and more recently vs Iran, plus general skill available in US R&D/military, while Russia never tested their S-400 systems in (real) combat and is notorious for poor maintenance/training.
Unless you equalize these 2 things it's a moot point. RU missile teams have had plenty of press about improving their operational effectiveness in the last year. AA has not.
Additionally, these systems aren't that sophisticated, it's GPS+inertial navigation+maneuvering+maybe some limited anti-EW. The rest is intelligence, EW, operators, etc. ATACMS was designed in the mid 1980s after all...