The only thing confirmed for now is that Caustic will be buffed (in whatever way) during the Legacy ninth season which began earlier in the month and will be concluding in early August 2021.

Is caustic getting a buff soon?

Both Fuse and Caustic will be getting buffs in Apex Legends Season 10 to help out their effectiveness, as they have been fairly lackluster during Season 9. Apex Legends is about to get even more interesting in Season 10, as we are getting new Legend Seer and various changes in the patch notes.

When did caustic get buffed?

It should be noted that Caustic was buffed in the Season 10 update, where the damage of its Toxic gas was increased significantly. Considering how pivotal Toxic gas is for this Legend, this buff made it a bit more viable.