Even 25% humidity can still affect the filament depending on how and where you store it. Also it doesn’t always come properly dried. Different batches of same filament can react differently (not usually, but does happen). Never know when a brand uses a different supplier/manufacturer.
You could take off the bed and make sure the y axis are moving identically still.
You can lubricate the drive screws inside the rail, but I really don’t think that that’s your problem or will make a difference. It’s recommended to do yearly. I need to but still haven’t gotten around to it.
Here’s a thread about maintenance: How to maintain the snapmaker in perfect condition?
-S