Cutting fat as a powerlifter is a balancing act. Lose weight too fast or too carelessly and your strength goes with it. Done right, you can drop fat, hold onto nearly all your strength, and even move better for it. I have walked plenty of lifters through this without watching their numbers fall apart.
Go Slow to Keep Your Strength
The single biggest mistake is cutting too aggressively. Crash diets strip muscle right along with fat, and muscle is where your strength lives. Set a modest calorie deficit and aim to lose around half a percent to one percent of your body weight per week. Slow and steady protects the muscle you worked years to build.
Keep Protein High
When calories drop, protein becomes even more important. Keep it at one gram per pound of body weight or a little higher. High protein in a deficit tells your body to hold onto muscle and burn fat instead. It also keeps you full, which makes the diet bearable. Pull most of your cut calories out of carbs and fat, not protein.
Keep Training Heavy
This is the part lifters forget. If you want to keep your strength while cutting, you have to keep lifting heavy. Drop the weights and switch to light high-rep work and you are telling your body it no longer needs that strength. Keep the heavy singles, doubles, and triples in your program. You may need to manage volume as energy dips, but the intensity stays.
Cut slow, eat your protein, and keep the bar heavy. Do those three things and you can come out of a cut leaner without leaving your strength on the table.