If you train long enough, you'll learn that you need to do a warm up set and sometimes you'll need to alternate your weights and reps every week/month. Maybe he's at his low weight high rep phase, or he's just finishing off or warming up his chest with flat BB.

And 25 kg on each side is a lot to a beginner. I've seen beginners starting on 5kg on each side and they are struggling and shaking and need someone to spot for them. So don't say "25kg is not much" because it's discouraging the beginners reading your post.

I remember starting off struggling for 15 kg on each side when I was started lifting for a few months...it took me a year to reach 20kg on each side at 8-12 reps on flat and incline.
Sometimes when I bench, the weights are so heavy that the pressure of the bar is pressing against my thenar muscles on my hand (the part just before the thumb) and it hurts like shit.

It does and patience is a must!

Olympic bar is 18Kgs btw!

the one in mmu melaka uni, is 18kg.
where r u studying?