There could be a flag to include spaces in generated passwords. As far as I read, there should exist no problem in using spaces in passwords: on the contrary, they are yet another source of entropy.
Leading and trailing spaces can actually be a problem for printed passwords that need to be manually copy/pasted. Consequently, it could be a good idea to have an additional flag to avoid leading and trailing spaces. Anyway, as long as it’s BitWarden to fill the input fields there should be no issue at all even with leading and trailing spaces.