This is a good test to run for various materials. Birch plywood from various sources is quite variable and I believe testing is necessary on every batch I get. The testing is time consuming, but wasting material is too costly to just “wing” it.
Keep in mind Baltic birch and birch are two quite different products. The most common issue with plywood is that the glue they used isn’t laser cuttable, or there are voids/fills that aren’t laser cuttable. Cleaning the edge will always have to happen - your using fire to cut wood - but it sounds like your issue may be the material as well as the 40 vs 45W tube.