smelting one cactus in java gives 1 xp so smeling one stack of cactus is enough to raise your xp from lvl 0 to 5 while in bedrock it smelting one cactus gives 0.2 xp one stack raises xp only from lvl 0 to 1 thats 5 times less than java i have attached a link for one stack smelting tests for each version

java 1.20.1 
bedrock 1.20.15

(the lastest releases at the time of writing the article)

i hope you fix it if its a bug if not please reconsider it or buff it

thx for your time...