A bright, high altitude light--NOT an airliner--moving at constant speed and brightness, then disappearing at same apparent speed.

Date of sighting: April 5, 2021 Location: Middle of Big Bend Ranch State Park, TX Coordinates: 29° 24’ 44” N, 103° 59’ 60” W Time: ~21:37 local time Weather: Clear  My wife and I were camping at a remote campsite in the middle of Big Bend Ranch State Park in SW Texas, a very remote park. This was our second night at this location. The sky was dark—the moon had not yet risen—on a clear night. And it was very quiet… no wind, little insect noise.
 We were sitting outside, enjoying the night sky, chatting. As it happens, I had just commented that we had not seen another human being, or even one aircraft, since setting up at this location.
 Then we both returned our gaze back up to the sky and saw it: a bright light moving west to east, just a bit north of our location. I.e., not directly overhead but nearly. My wife described the light as “yellow” and “triangular, with a point." To me, it appeared more orange, and more spherical. The speed of the object might suggest a commercial airliner at altitude, but it was much brighter, and we would both say "bigger," than that. The light was not blinking, and there was no noise.
 We watched it move across the sky for 10 seconds or so… long enough for us both to say, “What is that?!” The brightness was constant across this initial period. It then faded, still moving east, diminishing gradually from the bright light to a disappearing dot of light over the following ten to fifteen seconds.
 The object maintained the same course, and the same apparent speed, as it disappeared. We both found this aspect of the trajectory very striking. If the object was at a constant altitude, one wouldn't expect the light to diminish so quickly. It didn't traverse an especially large arc of sky. It was nearly directly overhead over the entire length of the observation. Likewise, if the light was disappearing because it was gaining altitude, one wouldn’t expect the heading and speed of the object to appear constant.
 This event happened during the middle of a two-month camping trip through the American West. We’re now back home and able to file the report. These notes were made contemporaneously with the event.