rulebook is here if you want to see for yourself: I did some citations https://cdn.sanity.io/files/dsfx7636/news/b2626c898b248fe08f7cf5425d5b54e3deb1db31.pdf
According to this rulebook, there are classifications as to bugs, but only two are relevant here (classifications can be found in section 7.1):
- Game-breaking (in the seemingly inaccessible to public Esports Bug List)
- Non game-breaking, but still game altering (Major Bug + Unknown Bug)
Riot officials can replay round without a Challenge from the HC if 1) no damage has been done and it's a non game-breaking but still game altering bug, OR 2) it's a game-breaking bug, damage CAN HAVE BEEN DONE (7.2)
IF damage has been done and it's a non-game breaking but still altering bug:
HC has to use a Challenge "within the first twenty (20) seconds of a Buy Phase of the round immediately subsequent to the impacted round... in order to use a Challenge, the Team must have at least one (1) remaining Timeout for the map. If the Team does not have any remaining Timeouts, the Team may not request a Challenge" (9.1)
In the case of FPX/XSET, we don't know if it was a game breaking bug or not (randoms on the internet claim it as one though), but because it was the last round, Riot MAY HAVE made an exemption to not taking initiative IF IT WAS NOT a game breaking bug (there is no next round to call out the bug)
Unclear what official procedure for the Vyse indicator bug is, though, because we don't have access (or, at least, I'm unaware of where it is) to the Esports Bug List
Discord