I could have sworn that this issue had been raised in the past, but I must have dreamt it.
Simply put, this support is destroyed whenever an event support enters the board, apparently treating that support as being “cast” but not actually preventing the support from coming into play, as per the triggered effect from the Pact. This occurs on both treasure and gold supports that come into play, as well as the permanent supports.
Card: Pact of Negation
Type: Support
Rarity: Masterpiece
Text: When this support is on the board, the next card a player casts is Destroyed and it’s [sic] effects do not trigger, then this support is Destroyed.
