Riot Games reworked some of Viper abilities previously in order to make her more viable when compared to other controllers but it appears that wasn't enough and devs are looking for more in patch 10.4.
Valorant's role spread among agents is rather asymmetric with the number of duelists being higher than that of controllers and sentinels. Therefore, it is easier to notice outliers in the smaller agent sub-pools. For example, Brimstone is often seen as the must-have controller while Viper is at the bottom of both that list and not really appreciated overall.
It was for this reason that the fume-employing doctor was partially reworked in patch 1.02 where she received some major buffs to Snakebite, which starter making enemies fragile and Smoke Screen, which now burned through walls. However, this was not enough.
Viper still had to be extremely precise with her smoke unlike the main competition, Brimstone and Omen, who can literally choose where to pop them without ever leaving the cover.
This issue and many others were posted in a lengthy Reddit thread as a player explained her problems. Thankfully, the thread caught enough attention to see a Rioter's response.
Altombre noted that the balance team "has been talking about Viper a lot" meaning that she is closely monitored along with her performance. Furthermore, the team is apparently planning to introduce more buffs to the agent in the upcoming 1.04 patch.
That is all the information that was available at the time though since "it's not all set in stone yet, but that's the plan". It remains to be seen whether this will be simple number tuning or more on the rework side like the 1.02 changes.