Today's story time is brought to us by Zyra P cooldown:
Zyra P's cooldown is not actually implemented as a normal cooldown like "go on cooldown for 12 seconds" but instead as "number of 0.25s ticks". This is defined as 50 ticks at level 1, then -1 tick per level. With 0.25s ticks, this should come out to 12.5s-8.25s total cooldown.
Except, due to server framerate, a 0.25s tick is actually a 0.264s tick. This means the effective cooldown actually becomes 13.2s-8.712s. Despite this, the spell still calculates itself as if it's using 0.25s ticks.
But also, the server actually waits an additional 0.25s tick (really 0.264s tick) afterwards before actually spawning the next seed. This brings the real effective cooldown up to 13.464s-8.976s.
In order to account for this, the game does a bit of fudging for the visuals. The icon cooldown indicator simply adds a flat 0.75s to the intended value to get it to match up better. This is mostly accurate, coming out to 13.25s-9s, but is still not perfect, although this indicator is purely visual so it's not like you're gaining or losing any seeds by it being inaccurate. You can also see the difference, as at level 1 your seeds will noticeably wait a bit after the cooldown comes off before spawning, while at level 9 it's almost immediate, due to the closer timing match.
Meanwhile, the tooltip tried to approximate the cooldown differently, but only listed it as "13s / 12s / 11s / 10s / 9s @ 1 / 5 / 9 / 13 / 18". The tooltip has now been changed to 13.5s at level 1, then -0.25s per level (9.25s at level 18), which while still not exactly accurate is still an improvement.
Also very much worth noting that they do in fact possess the ability to make this spell work like a normal cooldown, like other passive cooldowns, but they just chose this instead, along with all the bandaids necessary to cover up its side effects. I was hoping that these data changes would be indicative of such a rescript, however a new calc was also added that corresponds to the "50 ticks -1 per level" formula, implying that this tick-based system is still in place, and it's just a visual improvement on the tooltip. But, I'll need PBE to come back up to be able to notice the presence or absence of these side effects to know for sure.
edit: PBE actually came back up right after I posted this and yep it's functionally unchanged and still wonky