Patch 11.1 of World of Warcraft will automatically convert leftover Bronze Celebration Tokens into Timewarped Badges. This conversion, at a rate of 1 Bronze Celebration Token for every 20 Timewarped Badges, will occur upon players' first login after the patch launches.
The World of Warcraft 20th-anniversary event, featuring the acquisition of Bronze Celebration Tokens for purchasing revamped Tier 2 sets and anniversary collectibles, concluded on January 7th. Any unspent tokens could already be exchanged for Timewarped Badges (used in Timewalking events). This automatic conversion ensures players won't be left with unusable currency. Blizzard has confirmed no future use for Bronze Celebration Tokens.
This convenient conversion will happen automatically upon logging in after Patch 11.1's release. While the exact release date remains unannounced, February 25th is a strong possibility, given the timing of other in-game events (Plunderstorm and Turbulent Timeways). This means the conversion will likely occur after the second Turbulent Timeways event concludes. Timewarped Badges obtained through this conversion, or otherwise, can be saved for future Timewalking events as no rewards purchased with this currency are being removed.