There's a decent argument for using today's words even for settings that are no the current world. But for fantasy specifically I find it breaks immersion quite a bit. I'm not convinced by the "language changes over time" line of argument. If you take it to a bit more of an extreme it would also be fine to have characters say "cool" or even use some gen-z-ism etc, because hey words change meaning over time after all.

However, I'm also aware that I'm kind of a hypocrite because I'm totally fine with current world grammar and punctuation for example.