In a Dutch oven or similar large, deep pot, heat the bacon over medium-low heat. Continue to cook until the bacon is crisp and the fat is rendered, 10 to 12 minutes. With a slotted spoon, remove the bacon from the pan and transfer to a paper-towel-lined plate. Lightly pat dry and set aside.
Add the butter to the pot and let it melt. Set aside 1/4 cup of the sliced green onion tops for serving, then add the remaining green onions. Add the celery and bell pepper. Cook, stirring occasionally, until the veggies begin to soften, about 5 minutes.
Stir in the garlic and Cajun seasoning. Cook until the garlic is fragrant, about 30 seconds.
Sprinkle the flour over the top. Cook, stirring constantly, for 1 minute. Slowly pour in the milk, a few splashes at a time at first, stirring out any lumps. Stream in the rest of the milk, then add the broth, corn kernels, cream-style corn, potato, and salt. Stir and bring to a low, gentle boil. Let bubble softly until the potatoes have softened and the mixture is thickened, about 20 minutes. Every few minutes, stir the pot, running a wooden spoon along the bottom to prevent sticking.
Stir in the salmon. Cover the pot and let continue to simmer gently until the salmon is cooked through, about 5 minutes. Taste and adjust the seasoning as desired. I added a few pinches of salt.
Remove from the heat. Serve hot, sprinkled with reserved bacon, green onion tops, and a dash or two of hot sauce as desired.
Notes
TO STORE: Refrigerate in an airtight container for up to 3 days.
TO REHEAT: Warm gently over low heat, stirring occasionally. Avoid boiling.
TO FREEZE: For best results, freeze before adding the salmon and stir it in fresh when reheating.