Chainring rubbing frame after tightening cranks. What should I change?
The first thing to do if you haven't yet is confirm that the taper bore on the drive side crank is still in good condition. Take it off, hold it up against a light, and look for any deformation. The squares formed by the two ends of the bore should be in perfect alignment. Because square taper cranks are a press fit, there is nearly no tolerance for deformation here before the crank has issues with coming loose or falling off.

What you're experiencing here is one reason, really the biggest, why I don't like to grease tapers. You get unpredictable things happening with how far the crank sinks on, and it seems like it makes it more likely to be an issue over time. Some hold the theory that the combination of greasing spindles and re-tightening the bolt can contribute to or cause the cranks failing outright over time, which is a rabbit hole of a topic, but google Jobst Brandt's writing on this if you want to understand that argument.

If the bores are still in good condition, and the chainline was right before and now it's too far in in front, then getting a new BB that puts the chainline correct again is a fine solution, barring any issues with tight clearance between the ring and the frame. Usually I don't really see anything less than around 3mm between the frame and any part of the crank as acceptable, although it's a line I'd be okay pushing on my own bikes.

The cheap and simple solution if it works is to put a 2mm or so spacer under the shoulder of the drive side bottom bracket cup. This will make the cranks asymmetrical by that much, but most people wouldn't notice. The reason this doesn't always work is that many left side cartridge BB cups have a lip on the end of the threaded section that will keep them from being able to sink into the BB shell to correctly secure the cartridge once the spacer is in place. (Usually the end of the threaded section pokes out just a little bit, with the spacer it will need to be below level of the shell face just a little bit.) Spacers such as this are a common bike shop item. Using a single 2.5mm Hollowtech 2 BB spacer is a likely thing to be able to find, or a freehub body spacer, or a cog spacer off a used cassette, or a 1.8mm 10->11 speed spacer, or a 1.8mm Shimano cassette spacer for Mavic road wheels, etc.

If the left cup does have that lip, you may be able to grind it off without weakening the cup too much.