3 pod in Commander Open Play

I play Golos superfriends, against Sisay Legendary, against Meren. It started to get buggy mid-game when the Monarch was introduced (which messed up the card alignment).

My board became insane with multiple walkers, enchantments, and creatures. There were about 60 permanents on my field including emblems, then I ultimate'd Sorin, Grim Nemesis, after Primeval's Glorious Rebirth, multiple instances of Ajani, the Greathearted proliferating as well as Nicol-Bolas, Dragon-God proliferating too using that same effect. Sorin's ulti would have created about 60 vampire tokens.

The game then stalled, then restarted, and began to replay the first four turns by itself.

Never seen anything so crazy in my life.

Error report has been sent after the game crashed.

I was playing an opponent and they had Anje Falkenrath as a commander and played library of Leng. They had a creature of which I cannot remember but it had the ability that whenever you discarded a card with madness it got +1-+1 until EOT. So my opponent was using Falkenrath with Leng to discard a card to the top of his labrary and re-draw it using Falkenrath's ability to infinitely pump the creature and swing for lethal trample damage with the pumped creature.

My first thought was that the discarded card he was discarding was not revealed. So how did I know he was actually discarding a card with madness to the top of his library. So I researched Library of Leng Rulings and it noted that the discarded card did not need to be revealed unless another ability states that it needs to be. Which I get but it still didn't make sense because in a paper game how would the opponent know the card being discarded has madness. It made no sense. And then I checked the other rulings for Leng and it notes that a discarded card can only go to the top of the library if it's being discarded to an (ability) otherwise it would go to the yard. Well, my opponent was discarding the "madness card" to the top of their library as a part of a cost to activate Anje's ability which the Leng rulings say that it cannot go to the top of library, only to graveyard because it was discarded as part of a "cost" not an ability.

So there are two bugs I see here with this scenario.

-The madness card was never revealed to prove it had madness to your opponent.

-Second as I read it, Anje and Leng cannot work together when discarding to Anje's activated ability "cost" of tapping and discarding a card to draw a card.

This happened on MTGO and the interaction worked online and I was not shown the card being discarded ever.

I believe this to be a bug.