I think the Great Permian Extinction was a multiple condition extinction up to and including heavy Cosmic Ray Bursts or density of near interstellar space.
The P-Tr Extinction happened about a year ago (Galactic Year) which means we are now in the same general position in the galaxy. Since the galaxy is spiraling inward towards the center, not the exact same position.
Millions of Years
Extinction events have been slowly decreasing as the Sun gets closer and closer to the galactic core. The P-Tr event is the largest extinction event over the last two galactic years. It sticks out like a sore thumb.
As the Sun moves closer to the galactic core it enters denser areas of galactic space. With this density, the Sun's heliopause shrinks, it compacts making it gain internal pressure. 225-250 mya the Sun was in a lesser dense area of the galaxy, the heliopause was extended and there was less protection from cosmic ray bursts.
As the Sun plows thru interstellar space it causes a bow shock to form in front of it. The resistance of that bow shock determines the compaction of the heliosheath. One galactic year ago there was less resistance in the bow shock and the heliosheath was extended and sparse compared to now.
More stuff got thru, less stuff being deflected, higher cosmic ray saturation. This explains the high rate of extinctions tapering off over time. The P-Tr event was a near burst that heated the Solar System causing multiple reactions on Earth.
The Local Arm (Orion Arm) is colliding/merging with the Sagittarius Arm from the Perseus Arm. We are still in an area of sparse interstellar space compared to the density of space when we meet up with the Sagittarius Arm. Space is also slowly getting hotter as we get closer to the galactic core.
I'm not saying this caused the P-Tr extinction but it probably contributed to it. A GRB (Gamma Ray Burst) does explain the high spike in the extinction events timeline.