Lunge your horse before you ride not for too long
My horse does the same thing, usually we just let her take a while to warm up before actually focus on her moving forward, then I usually just push her through the patches where she is bucking. Sometimes she is better if she has been lunged first or it is her second ride of the day so maybe try that🐴 hope it gets bette
I would give him a special treat and/or graze when he does really well. Don't be so quick to offer treats. Maybe this would be something for him to look forward to.
To help and get some energy out free lunge him before your ride. And work on grown work and your bond because ur horse isn’t lazy if he bucks, try to spend time with him and create a stronger bond so he respects you.