Yes, it's true. There are only so many R voters and they are being drawn out of safe R districts to flip safe D districts. There is a lot of predicted light pink within the rural parts of the triangle/central TX right now when before it was all ruby red.
I've seen serious analysis that shows only 3 of the 5 Republican gains are likely to pan out. They made the error in fully flipping Casar, Green's, and a rep by Dallas' seats (not Crockett) but just barely nudged Cuellar and Vicente Gonzalez's seats rightward, even though those two are probably the most difficult to dislodge. Team Turnip honestly believes their gains with Latinos will stick, so they didn't think they needed to mess with South Texas much. Trump won both of those seats while the Dem reps both won by several points. In a likely 2026 environment, with an 8 - 10 point R to D swing, they likely stay blue.
That says nothing about the rest of the state, where the R vote is being spread out to attack those three deep blue seats. Surprises are possible.
Meanwhile, if it comes to pass, the 5 flips from R to D targeted in California are highly likely to play out.