When a player leaves and a computer enters in his place, he does not play.

bots cant play this game but I think due to the general feature when people leave bots take their place.

Hello,
bots can of course play 99 just fine.

What you reported here is indeed a minor bug, but if you want the bot to continue playing for the person who left, save and restore the table, and this will resume the game as expected.
On the other hand if you don't care about keeping the same number of players, you may also just kick the bot out of the game and resume playing without the person who left.