Less than 10% of congressional districts this year will be competitive (defined as the most recent presidential election margin was within 10 percentage points). Only 41 seats!
I haven’t really seen a realistic plan to do it though.
Even in my home country, which is european country with proportional system and no gerrymandering, such deviation is higher (< 2%) due to rounding effects.
Gerrymandering is main issue in (some) state elections (e.g. Wisconsin 2018 is egregious example), not federal elections.
The bigger problem is that it incentivizes partisanship and extremist views in uncompetitive districts because the representative is effectively decided in the party’s primary election, not the general election which has higher turnout and a more representative electorate.
Also the fact that 90%+ of congressional seats are safe except for the occasional primary opponent discourages accountability. Our districts are so distorted, they make no geographic sense. And it means a large percentage of our population is permanently disenfranchised, which dampens voter participation. It really is one of the biggest structural problems of our democracy right now.