I did go look. If the claim made is supported by that page, I sure didn't see it. You may also go look. We're all using the same link here, and it's already been supplied.
[EDIT] Incidentally, I'm not making "the opposite claim". I'm saying I can't find support for their claim (or the opposite, in fact!) on the link they, not I, supplied. That is not the same thing as making the opposite claim.
In 2020, 222 of 435 seats were D, so 51%. The popular vote was 51.5% D, so the D's should have an extra 2 seats.
In contrast, 538's analysis shows that the R's have an advantage of 52% of the seats 538 identifies as "leaning" (with 68 seats left to have lines set).
538 shows the D's doing slightly better so far in the current redistricting balance, but they are still behind the R's on balance.
You need to read 538's work if you think corrral is wrong.
Are those findings somewhere else? That particular page does not clearly support that claim.