ᐅ How can I reinforce Bobby shelf boards that are sagging?

Hello everyone, I have a problem with the shelves from Bobby sagging increasingly despite normal loading. The shelves are standard about 80 cm (31.5 inches) wide and made of relatively thin wood-based panels. I would like to know how I can stabilize or reinforce the individual shelves so they don’t sag any further. What methods are recommended here, are special supports or reinforcements advisable, or should I consider replacing the shelves? I look forward to your tips and experience!