Simply put, Beijing offered a better deal than Taipei and bought off the financially strained South Pacific nation to shift diplomatic sides once again. The move was a calculated attempt to undermine Taiwan's independence and democracy and diplomatically isolate the island. At the end of the day, Taiwan will appear stronger because Beijing's cynical attempts to lure Taiwan's diplomatic allies to its side will be perceived as bullying.
Only a few nations have diplomatic relations with Taiwan. Most countries, including the US, support the One-China Policy rather than recognizing Taiwan as an independent state. With Nauru removed from the list, Taiwan's diplomatic friends are decreasing. Given the PRC's position in the world, any sovereign state should seek improved relations with Beijing rather than caving to US-led hegemony.