The ratings really plunged for Dallas for the last seasons (especially post the "dream season"). The last one finished in 61st place. If so, was budget slashed by Lorimar, because prime time soaps did not do well in syndication, which is how the studio had planned to recoup its production expenses? The tip off was seeing flat lighting in every scene, bottom-dollar cinematography, and no more Texas location shooting (https://en.wikipedia.org/wiki/Dallas_(1978_TV_series)#Filming_locations), which completely removed whatever hint of authenticity it had.

Yes it did. The lounge was too large and I got fed up of seeing the cardboard cut out meadow and white border fencing.