3 things are related with the mouse control:
1. game settings
2. activated configs and settings in ReaSnow S1's
3. mouse settings
so if the mouse control changed, there must be some changes in them or at least in one of the 3.
our recommendation is:
1. restore ReaSnow S1 to its defaults with our Flash Tool
2. then add only Apex Legends' config in it, do not change anything in it, and do not add other configs or macros too.
3. it's better to try another mouse, it might also be caused by some changes in the mouse.
4. try some other game, and check whether you will face the same trouble or not.