De Bruyne definitely isn't the player he once was, but I think some of the criticism he's getting is still harsh
Although De Bruyne isn't performing at the same level he was in years gone by and his increasingly frequent spells out injured are raising questions of whether or not it's worth it for Man City to keep him, his actual contributions when he does play I think are being a little bit overly criticised and taking too much of the flak for City being generally poorer this season.
For one thing, there's chances created. De Bruyne has played 694 minutes of PL football this season and created 41 chances - so that's 3.43 chances created per 90 minutes. As far as I can see that's the best ratio of chances created per 90 in the league, with Saka being the closest behind him at 2.96 per 90. Of course, chances created is a little open to interpretation, but it does also seem to tally with City's shot conversion apparently being down from 11% last season to 9.2% this season, suggesting that their fall off is at least partly down to failing to convert chances rather than just struggling to create them. De Bruyne may have declined, but if you just looked at this season's passing stats in isolation you'd say it seemed like he was still doing a more than adequate job in his creative role.