So I just did my luckiest run ever with shield spirit+cleavers (stopped at floor 62), and here is little collection of bugs I've encountered on my way:)
First, you can change between backpack and the map while attacking in combat (cleavers take quite some time to do their things), and when you do so, "End Turn" button disappears. It will return if you go to the map and back again once you finished attacking though. By the way, I can't even tell for sure how many times I've accidentally clicked End Turn instead of actually making my turns, can't help but click this sneaky button sometimes, not even sure if its positioning or its look or what else:)
On the floor 40 I somehow got scammed for my key, opening a door on Floor 39 and expecting The Swamp on 40-42 segment, but got into the Caves instead. Maybe that was my missclick although Im almost sure I picked the right one, but maybe.
SFX volume option resets after refreshing the page, while still showing the old position of the slider. So things are getting loud until you move it back and forth a bit:)
There is also a bug I've mentioned here before, with relics sometimes stop applying their effect after reorganizing during combat.
Sometimes map can generate a healer (I don't think I've seens the chest like this but might also be the case) with a locked door you don't have to open because there is a free passage from one of the other sides:)
Now a couple thoughts, of course everything in the endless run is not supposed to be perfectly balanced but it still shows some flaws imo.
Poison has mediocre effect when used by players, even if you manage to find multiple poison arrows in an archer build, but completely destroys players with no reliable way to counter that (other than OTK anyone with poison). The fact it stacks and doesn't really go away means pretty high numbers eventually, but for monsters and their life pool its far from being effective compared to direct hits of certain builds, and for players its 1 to 3 turns before you die even with max life of 200 which takes like 50 floors to build:)
Burn is something players don't even have access to, but also destroys a lot of builds that are not block-heavy or have too much damage to care:)
Character max life in general seems pretty weak as you progress, even in regular magma core its already pretty non-existent with monsters damage numbers in there, you yet again need high block or damage. Ways to recover life are also a bit limited, but there are some in case it would be relevant at some point:)
Vampirism counts as a separate hit on weapon use, so you take damage from spikes twice. This feels pretty bad in general, there is not too much sources of this stat and it would be nice if it ignored spikes like the arrows do.
I'd really like to see some gold-based weapon at some point (to scale your damage by hoarding more gold), even without piggybanks and other stuff you eventually have hundreds of gold:)
Swamp area is good because you have a chance for badger forge events here, which otherwise you can only find later in the magme core. But it is pretty frustrating sometimes to not have a single one in multiple swamps, like it took more than 40 floors for me to find second rage upgrade for a weapon and it wasn't even a swamp :D Would be nice if you'll have a guaranteed forge once per swamp if you decide to go there, as its also has harder enemies than the caves imo.
Overall game is great, can't wait to see and try more stuff (and I still have plenty to experience, game just doesn't allow me to become a mage yet for example :D).