Given they've only announced the creation of 15 brigades (~3,000 per each) to replace the units they'll rotate out, you're left with the question of what the other ~455,000 are for...
Wordgames wordgames wordgames, as it is always with you. All the sources specify that part of that number is to rotate out soldiers who are just due to sheer length of the war, not even wounded. What part? That's anyone's guess, and i consider yours worthless FYI.
Ukrainian armed forces in total, depending how you count and who you ask, consist of 500k to 1.3m warm bodies total, so 450k for rotations alone is perfectly reasonable, meant to replace only the part of personnel who are not in support roles but indeed in more exhausting circumstances.