Is it correct to say “ that’d be a problem”

Thank you!

it's the usual difference between conditional and future tenses, so read up on them.

that'd be a problem ... if something were true (but it's not)

that'll be a problem ... if something happens in the future (and it just might)
or, it might always be a problem

Or is it “ that’ll be a problem”

What’s the difference?
Thank you