It'll be best to tag your flowers in the appropriate block and item tags for best compat with other mods and to work with vanilla bees.

You can find the flower tags here
https://minecraft.wiki/w/Tag

Short summary of the tags
minecraft:small_flowers <- 1 block tall normal flowers
minecraft:tall_flowers <- 2 block tall flowers
minecraft:flowers <- all other kinds of flowers

Thank you! It will be done in the next update.

https://modrinth.com/mod/many-flowers/version/OIIWERoL