Celery freezes?? That’s a surprise, I would think that being so watery it would thaw like mush. Maybe chopping it makes the difference.
I chop it and freeze it loose on cookie sheets, then into ziplock bags. Take out what you need as you need it. I add it frozen directly to ‘stuff’ and I’ve not noticed it being mushy. Maybe cooking it from frozen helps that? It’s just going into soups and stews and casseroles, anyway. I’ve never tried to use it thawed again, now that you mention it...
I freeze the leafy celery ends along with other veggie trimmings for chicken or veggie stock. With those, I just throw them all together in the bag; carrot ends and peelings, broccoli and cauli stems, onion ends, etc.