I drive a 2012 Honda CRV-V. When I accelerate through 25-35mph, there is a slight shudder/rattle. It ends when the transmission shifts up. It’s done the same thing for the past 20k miles (or more), hasn’t gotten worse or better, and doesn’t do it in any other gear.
If the entire vehicle shudders, it’s time to have it professionally inspected. Could be wheel bearings, axle or other steering/suspension parts. Does the sound/shudder behave differently when you lightly apply the brakes as it happens?
There are a lot of possibilities including but not limited to a loose heat shield (yup, even FWD vehicles have heat shields), a bad motor mount, or a bad serpentine belt tensioner. Have you ever opened the hood, revved the engine, and listened? If not, you may want to try it. Just don’t stick your hands into the engine compartment unless you know what you’re doing. You could lose a finger. Your vehicle likely has a “drive by wire” throttle plate, so you’ll need a friend to rev the engine with the pedal while you listen under the hood.
You should also drive the car up on ramps and, with the engine off and the parking brake on, and, with gloves on, try shaking things, especially the exhaust system.
There is technology wherein a tech can place microphones or sensors at key points and record the vibration happening. It can provide a good sense of where the rattling is coming from.